I think it's ridiculous that people are complaining about XY being on the 3DS, it had to happen sooner or later (as a matter of fact, I was unhappy that 5th gen wasn't on the 3DS). The DS is dying, there's no reason to continue to support it. By that logic, 4th gen should've remained on the GBA because not as many people owned a DS. Besides, the 3DS could use more games, they've got a few good ones, but many of Nintendo's major franchises have yet to appear. And since Pokemon is a major handheld seller, it's only natural that they release one ASAP.
Anyway, if you don't have a 3DS, go out and get a job to earn one. This is likely the main reason the game was announced so early, to give people time to save up for one. There's no excuse not to make enough money in 6 or 7 months to be able to afford a 3DS and XY if you have a job, you can make that much alone in about a full week's worth of work (40 hours) at minimum wage.