I am not sure it is the new thing, rather the culimination of a trend. A couple of reasons come to mind...all somewhat inter-related. A lot of it has to do with how impressionable new divers are. Why did I buy a conself IVX many eaurs ago? It was a great regulator but I got one because my instructor had one and recommended it.
The first is that some people like to be on the cutting edge of anything in sport, especially if it is perceived as having good risk to reward ratios. This is not limited to diving, think about adventure sports that are on the edge. Breath hold free diving is rapidly becoming the new craze...New divers want to emulate the best. Marketing people understand this impulse. Up until a few months ago, four wheel drive offroad SUVs were how people identified with outdoor high adventure. Most of these vehicles never leave a paved road much less get put into four wheel drive. In 2000 the Nissan XTerra was the hottest status symbol at UCSB as it defined the driver as an adventurer.
Second, what is cutting edge and dangerous yesterday is mainstream and trendy today; attracting more divers.
Third, there is the "cool" factor. Tech is cool and what diver wants to be a dork? (apologies to dork divers on the board). a few years ago a series of books came out such as The Last Dive, Deep Descent, Fatal Depth, that really described what I would call the sociology of deep wreck diving, a pursuit quite separate from Cave Diving. These folks were the high men of the sport and normal divers want to emulate them.
Fourth, equipment has gotten better, moved from limited production workshop to manufacturers, and costs have dropped enabling people to buy equipment from more locations.
Fifth, certification agencies, such as GUE, use a tech approach and are certifying more people in the DIR tech based training. Other agencies follow. I recall that at the scuba show in 94 in LA I saw a Naui instructor go after a group of tech divers who had a small display set up, now it is mainstream.