It'll have been over three years since BW's release when X and Y come out.
Just seems shorter because of B2/W2. And because of all the Pokemon spin offs. And because we're hearing about the games ten months before they actually come out.
And because you're all getting older, and repeating the same experiences means less of the memory relevant chemicals are being released in your brains each time, so the passage of time seems shorter than it actually is.
Do something new every day, kids. You'll live longer. Well, it'll feel like it, anyway.
Gen 1-2: Two Years Gen 2-3: Two 1/2 Years Gen 3-4: Four Years Gen 4-5: Four Years Gen 5-6: Two 1/2 Years
It needs to be like this because with each generation there are more pokemon and gen v didn't even get a console game :/
That's because Gen 5 was a bit of a mess in general though. Not on a new system, no third version, 4th event legend released before the 3rd, spin-offs for DS (Typing, Conquest) and 3DS (Rumble, PMD), and you already mentioned no console titles. Not to say Gen 5 is bad, it's just kind of in a tough spot between the DS gen and the 3DS gen.