And by the way, there have been lots of people in the past who had no plans to get into tech/cave diving, but after diving enough that's what happened anyway.
I can attest to this!
One of the things that has made DIR-F so popular is that it is one of the only places where this level of skill is taught to recreational divers. You can get the same type of education from a cavern class as well. And there ARE some instructors who teach these skills and concepts (because there IS more to DIR-F than learning the kicks and the S-drill) outside of either DIR or technical classes. It's just not easy to find them.
As far as the DIR system being either necessary or useful for pure recreational diving goes, it is certainly not necessary. But improving one's skills makes ALL diving more enjoyable, and the team ethos of DIR makes it possible to go anywhere and jump in the water with someone with whom you have never dived before, and execute a smooth, coordinated and thoroughly enjoyable dive. I've done this now in several places. In fact, as I have read the horror stories of "instabuddies" and other buddy-related problems, I've been more and more appreciative of DIR as a system that, if you observe it, just prevents all of those issues.