I'd ban them anywhere they aren't necessary for actual serious exploration dives. When I'm putzing around on some sleepy little wreck that's 120' long, being circled repeatedly by someone on a whiny little machine drives me nuts. In those situations, they're the sub-aquatic equivalent of jet skis... pass me my gun and some rubber bullets.
.
I get that you are entitled to your opinion, and agree that on small wrecks etc they're not required, However it remains that this is still a sweeping statement.
I along with my group of divers use DPV's all the time on open water reefs, we can be out in the blue father off teh reef than those with out DPV's might be comfortable in going, we can interact with larger schoals of sea life, and the flip side sis we have freedom away from the none dpv divers - who in the worst cases will be on top of each other hanging on to the reef in a current or crowding a whale shark desperately trying to keep up. Personally I'm glad of the freedom a DPV gives to "escape the masses"
But suggesting that DPV's are only suited to long cave dives is incorrect
I've also had the great privilege of accompanying a renowned underwater videographer, on his DPV, with his mahoosive 8k video rig, and watched as he was able to interact with large oceanic Mantas' who were incredibly interested and circled and played with us out in the blue.
All that said DPV's as pointed out do take up a lot of extra space on the boat, especially as you should also be using a decent size redundant gas supply, because even as a buddy pair you are effectively solo. Also DPV's do need the dive to pay more attention as it's too easy to go deep or have a saw tooth profile, and some experience is need to be able to judge how to "pad" the back half of the dive to account for the front half of that dive