I rarely play live chess now but would be reluctant to advocate changes that involved more rating pts lost (and therefore gained by the winner) due to forfeit losses. And in live chess players occasionally disappear due to connection problems or problems with the PC they're using. Finally, I doubt if many players will like your idea of rating time losses differently than mates or resignations; at least I don't.
rating system

A rating is supposed to be an accurate image of a player's strength. Whether the player resigns early or plays to the end has nothing to do with their strength.
Intentionally abandoning a game is reportable under the fair play policy.
I would like oto take this opportunity to ask my fellow players, do you think the rating system ought to be changed so that players who walk out when they know they are beaten, are hit with a heavier rating penalty, also, should losses on time, be less rewarding or punishing than resignation or mate?