Alright, I can understand that to a degree. But the fact is physical actions are quite a bit different then mental ones. If you say you are a peerless warrior who can kill a hoard of enemies, I can see in your stats why and how that works, and you can go do that, in game, physically. However if you say you are are a very charming person, but then can't say anything but "Ummmmm..." whenever you are talking to someone. Or say you are super smart but only say and do stupid things, that creatives dissidence.
Now admittedly you can just cut anything like that out and replace it with a very shallow and poorly made system, like D&D does, but then you change the game from a Roleplaying game into a dungeon crawler, which I am actually fine with, and I would have fun with it, but there are actually games that do that better then D&D 3.5. And if you are complaining about my opinion based on the idea you want to play as a charmer it seems like you wouldn't like that. Or if you would, then it seems like you don't actually want to play as a charming person, but rather someone with magical mind control powers, which are actually done better in this very game then the diplomacy system does it.
This is made worse by the fact that the game basically isn't really made for diplomacy. In combat, as your example, you have many many complex factors that the game is almost fully based around handling your interactions. In diplomacy you have a single die roll with a few very simple bonuses. The fact is diplomacy is more complex then combat is, but has a much less robust system, if it had a similar or better system, Or even fleshed out in any way at all, then maybe that would be better (although to be honest I find it hard to imagine a actually good diplomacy system.)
Ultimately, if you like the diplomacy system, good, more power to you, you can be the party face, you're not even wrong for liking it, I just disagree with you. You don't have to be so passive aggressive about it though.