The best part of TVD is that no one is perfect. Good guys make bad guy choices and vice-versa- so I think Elena does the best she can- she's 18- she's having to make crazy adult choices in very extreme circumstances. Are they all perfect? No way. But I think those choices come from trying to do what's best.

I also think it's possible that a lot of the hate comes from the Elena/Damon relationship developing.