You don't even fight him... At least, I don't think you do? Am I mistaken?
Why does everyone hate Alder? He's a much better Champion than Wallace and Iris. Especially Iris.
Oh, I agree he is kinda bland, but Iris? Pft. At least Alder plays a role in the game, you don't do anything with Iris except battle her as the Champion. I like Alder because he actually does something else and not just battle you as champion.
edit: Yes, he was really easy to beat.
You have a point, but... okay, this is a really shallow reason, but I really like what they did with Iris's battle music. XD And, well, there's the surprise factor in that she pulled off a Wallace except the champion she replaced wasn't really too awesome in the first place so it didn't matter as much.
Also her whole space princess thing was pretty cool.