Mario, Mario Kart, classic come backs, Smash, Japan imports, Animal Crossing, killer 3rd party games, do not seem to interest you because maybe the visuals are not up to date or you just do not trust Nintendo anymore maybe?
So what would get you to purchase one? Or even consider it?
Well, for me it's very easy to answer.
I would consider getting a 3DS, (and would have considered getting any Nintendo handheld in the past), if only SOME games were ALSO aimed to adult gamers like me. Mario and any platform, Mario Kart and any "kart" game, Smash and any "Smash" game, Animal Crossing and Japan imports for kids absoulutely means nothing to me. My attraction to such games, be they well coded and produced AAA masterpieces or shovelware, or anything in between these extremes, amounts to zero.
If it weren't for the Sony PSP (four Metal Gear games, two Ace Combat, two Valkyria Chronicles, two Dissidia, Crisis Core, Danganronpa, Last Ranker, ...) I wouldn't have even considered purchasing an handheld at all for the rest of my life...
Now I have a Vita, and I'm enjoying games like Gravity Rush, Assassin Creed III, Metal Gear Soild HD collection, and the odd import JRPGs...
So, in few words, I find 3DS games too kiddish and/or too clearly aimed for casual consumers to be really appealing to me. If you add the fact that the 3DS is regon blocked, there's no way for me to truly enjoy such a device (or any Nintendo handheld device) even it I could get one for free.
And no, I'm not a Nintendo hater. I was one of the first guys in my city to get a SuperFamicom! ;)