The reason real dirt riders, not kids on dirt bikes, are buying 2Ts again is because a 2T dirt bike is just better. The 4 strokes don't have the power to weight ratio. A 4 stroke bike is heavier when compared to a 2T bike of the same HP (We'll just ignore the traction advantage that a 2T bike has on a 4 stroke and that tires last longer on a 2T).Those are little 2 strokes 250cc and down and they are only useful in dirtbikes.
2 strokes above 250cc for motorcycles have a hard time competing with 4 strokes on all fronts -- that's why you don't see them anymore.
I retired my last 2 stroke street bike 3 years ago, she was a TS200R. Great bike, parts became prohibitively expensive.
A 4 stroke is also more expensive to operate, harder to fix, MUCH more expensive to fix, much more expensive and complicated to "hop up" than a comparable 2T.
Another good reason to run a 2T is, if done right, a 2T is quieter than a 4 stroke. REAL dirt riders care about the environment.
For all the same reasons they use larger 2T engines in snowmobiles. Polaris and Skidoo make a 600 and 800/850 2T sled. The Skidoo ETEC 600cc makes 125HP and passes California EPA.
WickedATV can make you a Banshee based 700cc screamer that will still win at the sand drags against the factory 4 strokes.
I don't know where you're looking, but I see 2Ts all the time.