The rachni queen is a big thing that doesn't matter in Me3 and ME2 doesn't even matter anymore, ill explain this more in detail little busy right now
edit: Even if you let everyone survive the suicide mission it doesn't matter, thane and legion will die no matter what. and like I said about the rachni queen, doesn't matter if you killed her off because the reapers are like "lol we have a army of rachni pets anywayz" and jesus christ at one of the ending, just plain awful. I'm just really disappointed honestly.