Well at least you have now come back to clarify your position, Delete. So now allow me to address your points:
It didn't make sense for Jeff Bridges character to want Tony dead before Tony's, no pun intended, change of heart. He was the cash cow that was being milked for all it was worth. Plotting to kill him before hand made no sense.
Stane wanted to be head of the company (kind of alluded to in the award presentation - he had control of the company before Tony was of an age where he could handle it), so he could sell arms to anyone. As seen later in the film, he was willing to deal with anyone, something even Stark wouldn't do.
It is revealed that Stane paid the Ten Rings members to kill Stark, but they realized who Stark was and demanded a much higher price (Peppers bit of espionage).
My other problem is that the villain was just some greedy corporate guy in a another Iron Man suit. Compared to The Joker and Two Face how can that possibly be better? Old Robot Gordon Gekko didn't do it for me personally.
Thats a thing of personal preference (as you mention right at the end of your sentence) & not about the 3rd act of the film. And thats fine - if it doesn't float your boat, it doens't float your boat - its your opinion & you're entitled to it. I will never try to talk anyone out of their own personal tastes.
But for me, it fit perfectly within the confines of the story - a man who the Stark family has trusted for years has become corrupted by the power he once wielded & turns against them in order to regain that control. Iron Man has always had its roots heavily grounded in the industrial aspect - as in big corporations, and it makes sense that in the business world you are always trying to one-up your competition.
I found it tied in better than some random guy wearing make up appearing from nowhere, terrorising the city. With that said, the reason I went to see TDK was because of Heaths Joker. He was a more entertaining villain than Stane (though the scene where Bridges pull Tonys Arc out was pretty awesome as far as tone goes). If he hadn't died or wasn't in it at all, I don't know if I would have bothered to see it because he was the best thing about it. Batman/Bruce Wayne played third fiddle to both the Joker & Harvey Dent, where as Iron Man/Tony Stark was front & centre the whole time.
