If your opponent doesn't want a threefold repetition repetition draw he has a choice not to agree to one, granted, most often this results in some loss of position or material, but he allways has the choice. Nobody is pointing a gun to his head forcing him to repeat the same mover three times.
Is it bad form to play for a draw?

Sure. If you are losing it would be a good idea to try to get a draw by repetition. Sometimes you can sacrifice a piece (or more) to achieve this. Keep your eyes open.

The person with the inferior position has every right to go for draw by repetition if that is possible! It is fully legal AND fully ethical. If the player with the better position cannot prevent repetition of moves, it is his/her discredit.
How can we blame one person for making the 3 repetitions? Isn't he also repeating his moves? That means he's equally to "blame." Basically, we have two players both repeating moves, neither willing to change their moves -- how can we single out one side when both are contributing equally to the repetition?

If you're losing and you have found a draw, take it. Otherwise - if material/position is even - it is uninteresting and uncreative to play for a draw.
Many pro players agree to draw in the last round of tournaments to keep their position, not wanting to risk anything, but this is robbing the world of great games and interesting ideas.

Totally fine, not a breach of etiquette.
You really have to work hard to get a contrived situation where repetition is in violation of some unspoken rules, but here goes: Going into the last round of a tournament, with white, you just need a draw to secure 1st place. (Your opponent, with a win, gets 1st place.) Of course you are not obliged to play for a win, but in your desire to get a draw, it is a slight violation of etiquette to play for a repetition in the early part of the game. This happened in a K-K match when Karpov had black in a Ruy Lopez, and Kasparov could have played for a repetition with Ng5-Nf3, forcing black to move his king's rook from e8 back to f8. It is not honorable to win a world championship via such a route.

If you're losing and you have found a draw, take it. Otherwise - if material/position is even - it is uninteresting and uncreative to play for a draw.
Many pro players agree to draw in the last round of tournaments to keep their position, not wanting to risk anything, but this is robbing the world of great games and interesting ideas.
But to reach to the position where you have the luxury of choosing to draw you already have shown a great game with intresting ideas. So you get a couple of games fewer that are intresting in a tournament, so watch two turnaments and be happy.
The person with the inferior position has every right to go for draw by repetition if that is possible! It is fully legal AND fully ethical. If the player with the better position cannot prevent repetition of moves, it is his/her discredit.
If this is the case, there is NOT in fact a superior position, they are both equal (at least for the abilities of the players involved.)

For me it depends on the position. If i cannot see a clear path to winning by either me or my opponent, then i offer a draw. If they do not accept i play on until they are ready to draw or another result comes from it.

I don't think playing for a draw is bad as draw is better than lost right?
Anyway who wants to lose a game especially in blitz?

Thanks for all the responses - I thought it might be more even but everyone seems to agree that playing for a draw by repetition when you are losing in material generally isn't breaching unspoken chess rules.

Material advantages don't always win in the endgame. And it is up to ur opponent to prove they can win if they don't accept the draw. I have won games i shouldn't have in OTB tournaments simply because my opponents didn't know how to play the endgame very well. I have also lost and drawn games for same reason, that's y i practice a bit more on endgames to improve myself.

Thanks for all the responses - I thought it might be more even but everyone seems to agree that playing for a draw by repetition when you are losing in material generally isn't breaching unspoken chess rules.
In my opinion, playing for a draw is always perfectly legitimate, regardless of the position and opponent. Tournament situation can make it a bit more complex, but still.
In the last round of a regional championship about ten years ago, I was a 1850 player playing a 2300; he was leading the tournament. A 2420 IM was in second place, a half point behind. They had drawn earlier in the tournament. For me, a half point would mean a 50% score, which would mean qualification to play in this group again the next year (plus I had never played a 2300 before). Difference in prize money between #1 and #2 was about $250, IIRC.
In the opening, my opponent blundered a piece for one or two pawns, and stubbornly played on. I was extremely nervy, played conservatively, got closer to an endgame but also used up a lot of time. With about two minutes left and feeling enormous pressure (but still objectively won), I offered a draw, which he naturally accepted. The IM had also drawn on board two.
Was it unethical to offer the draw, and thus hand my opponent the tournament win from a losing position? For years I thought so, but now I don't anymore. I had a reason for needing the half point, and if the IM wanted to win the tournament, he should have won their encounter himself.
In the opening, my opponent blundered a piece for one or two pawns, and stubbornly played on. I was extremely nervy, played conservatively, got closer to an endgame but also used up a lot of time. With about two minutes left and feeling enormous pressure (but still objectively won), I offered a draw, which he naturally accepted. The IM had also drawn on board two.
Was it unethical to offer the draw, and thus hand my opponent the tournament win from a losing position? For years I thought so, but now I don't anymore. I had a reason for needing the half point, and if the IM wanted to win the tournament, he should have won their encounter himself.
Having 2 minutes left being "closer to an endgame" you offered a draw and you were not sure for years? Come on, It is simply not enough time, you offer was perfectly reasonable and professional. I had 2 cases OTB, when people rated 250 higher than me offered me a draw in the endgame in roughly equal position having 5 minutes left, I had 1.5-2 minutes more. I agreed, of course. Why didn't they try to win ? - the draw wasn't good for their rating. Because their experience tells them that better get a draw than screw up playing blitz, they told me that themselves after the games. I, myself, in another game having a few minutes left, went from an endgame that was won to a lost one. Now I would just offer a draw at some moment.

Based on the circumstances of being at a material disadvantage, it was wise to draw by repetition. There's no dishonour in that decision. What I find a little cowardly, however, is in the last round of a tournament, 2 strong players will avoid risks and agree to an early draw so they can split the prize money. It's as though both are too scared to play for real because they know they could finish out of the money.
I had a blitz game where I was a piece down and played for a draw by repetition. In the chat window the opponent became quite abusive. I reported this and I believe the mods have given him a warning - my question is - is it poor form to play for a draw by repetition? I think that it's a game and you want to get the best result you can, and if that is a draw then that is what you should play for. I just wondered is this how other people see things?