What I believe: Yes. Yes it is, only for playing Pokémon X&Y, a mere game (with two sub-divides), and spending all that money, and this a game which you're probably gonna finish in a week, and also after the fourth re-playthrough, you'll get bored and move to something else.
What I feel: No. It's a game which you should buy only if you plan to play other 3DS games, or if you're a long-term Pokémon fan, meaning when the next Pokémon game is released, it's obviously on the 3DS, and so you'll get a long-term investment.
I've been a bit of a hypocrite on both my statements, but if you want to go back to the Wi-Fi Pokéworld, then yes. Buy 3DS and Y, along with Black 2 if your budget stands.