Well, I suppose there is the fact that I've been with Pokemon since the first games were released, and have no real reason to stop now. If I was going to stop, I would have done so at Platinum, but I've persevered with it, so I may as well continue to. I have two games on my 3DS right now - Tales of the Abyss and Super Pokemon Rumble - so I also need something to justify my actually keeping the console; it's been a tremendous disappointment thus far. I also know I'll get several hundred hours out of it, so it'll be worth buying it.
I also have high hopes for this generation. I found the fifth to be something of a letdown - there was a distinct lack of story, and after seeing all the praise I was actually expecting something to be there, and whilst Black 2 improved upon Black it was still below other, earlier games in quality - and I'm hoping this will redeem the franchise somewhat. I'm not big on graphics, but the leap to 3D offers endless gameplay opportunities, so I'm hoping for something new, which Pokemon hasn't really been since the first games. Changes have always been minor, so I'm hoping this time they'll be a bit more pronounced.