To be honest, Both Kaiden and Ashley had reason to be the way they were.
Ashley's grandfather was the only Human ever to surrender to an alien species, because of that she often got back-water and low-ladder jobs in the Alliance Military.
Kaiden has a sub-par bio-amp that constantly causes him pain, saying he is emo about it is like telling a cancer patient that they should just shut up and move on in life.
That being said, I saved everyone in all of my ME 2 playthroughs, so Im not exactly worried about who will and wont be in ME 3. But personally, I hope Tali, Legion, Thane, Garrus and Zaeed all make a return.
what, no Liara? sorry, but Im nearly 100% sure Bioware will have her in Mass Effect 3.