I don't think there is a problem with achievements or trophies in concept, but I find them a little pointless in their current form ... Effectively, they're somewhat similar to challenge based unlockables that used to be fairly common in games without the in-game benefit of these unlockables.
Personally, if it was up to me I would try to extend these achievements to include in game unlockables and possibly items that could be added to your avatar/Mii; while it is not the most exciting thing, it would be interesting to be able to give your avatar a green tunic for finishing Zelda (and whatnot).