Changing stuff around is expensive and it takes some "hard knocks" to understand its limitations. DIR as an equipment and procedural system has been vetted. The limits are generally known, the little things that can trip up a new system have either been found and eliminated or they have been recognized and their risks mitigated somehow. Or those issue just have to be recognized, eg. sidemount. I don't have any real need to reinvent the wheel. I appreciate being able to ask someone who's diving at my or higher levels how to either: manage what seems to be a new issue or manage a new peice of kit. There is a well trodden logical path ahead as far as I wish to go as long as it doesn't include sidemount, independent doubles, or a CCR.
FWIW, they've been using sidemount to explore certain tighter paths in the WKPP project. JJ has essentially developed an official DIR gear configuration for sidemount... they just haven't had the spare time to put it all into writing, since they don't consider it a high priority.