Bioware didn't give in. They didn't change the endings. They expanded the existing endings by filling in the obvious plot holes. They wanted everyone to pick Synthesis and the utter ridiculousness of that Synthesis has only been increased by the extended cut. Fans wanted endings that fit theme of the ME series. Bioware didn't offer that. They shoehorned a rushed ill conceived version of the Deux Ex ending onto a franchise that was thematically incompatible.
Mass Effect was about different races getting along in spite of their differences. The "optimal" ending throws that theme out the window and embraces the notion that the the differences races of the universe have to be the same to get along. That it requires and incredible suspension of disbelief. There was always a bit of space magic in ME, but Synthesis takes the concept to incredible extremes.
Mass Effect is the Matrix of video games. It started off great. It was full of promise and despite it's flaws was an exceptional experience. The same could be said for Mass Effect 2. However, by the time you reached the conclusion you wish you hadn't even wasted your time.
Side note: Bethesda "gave in" with Broken Steel. They even admitted that they botched the ending to Fallout 3.
