D5 for white

Im pretty new to the whole chess strategy monster, having played kings kight opening pretty much my entire "carrer" (1.e4 e5 2.nf3) and the ruy lopez because they are easy openings (i think everyone can understand :D)  but ive been looking into queens pawn openings and ive seen alot of people talk about the slav, semi slav, and the queens gambit opening

All of these openings are, as i understand, based around white controlling the D5 square.  So my question is, what is its strategic importance for white over any other square?

Not quite- most of those openings (d4 openings) are based on creating small but hard-to eliminate positional pluses for white and slowly but surely either squeeze or outmaneuver black to death. On that note controlling critical squares is rarely the objective of an opening but more a specific plan you come up with in that opening. There are a few opening variations aimed at controlling and dominating a specific square, I happen to play one myself, mine is quite rare so I shall give you another more common example:

In most of the D pawn openings kings indian specifically the d5 pawn releases the tension in the center and gives more space for white. He will often hold that move until later or release it early. d4 d5 c4 knf6 knc3 g6 e4 0-0 be2 d6 knf3 e5 **** white either holds tension with 0-0 be3 or takes immediate space with d5.