I think you'll find a lot more people starting to have a look at the dirt again. The manufacturers are putting BIG dollars into it again for the first time in years (i.e Tamiya and Kyosho) and in the end they tend to drive the market in the direction that they want.
Plus, I think its a cyclical thing. Off-Road was HUGE for 15 years, then On-Road was the new thing, now the wheel is turning back again with most of the current on-road drivers who have never driven a buggy in anger quite keen to have a try.