I actually prefer things the way they turned out. Ivypool has become one of my all time favorite characters. She risked and sacrificed a lot to help her clan and the others by becoming a spy and managing to fool the cats in there. I think the powers were more suited to Dovewing.
Who knows what things would have been like if their roles were reversed? I don't think Dovewing would have been able to pull off being a spy. I think once she found out she would have either found a way to stop going there or would have been found out in short order. Ivypool, I can kinda see the powers making her a little 'overconfident'. I'm almost positive she also would have used them to spy on the other clans as well which Dovewing refused.
As for Hollyleaf, a part of me wishes that she did have powers, but at the same token I did like her redemption 'arc' (not really sure it counts as a true arc since it wasn't really in the books and that short story I think left a bit out... I think (I can't really remember it all to well at this point)).