To answer your question, no, I don't tend to run those quests much at all these days on any diff, but over the piece I have run them at everything from R1 to R10 depending on what the group wanted, and before the server migrations I was part of a regular pug (not an oxymoron, there were a few of us "core" regulars, and others would join randomly/infrequently), and we ran those quests regularly on R10 probably 3+ times a week typically for the fun of it as it was something different and interesting. I don't think we were particularly special or alone in that at the time, but eventually the novelty wears off I guess, as mostly now if I do see them up for a PUG it'll generally be for R1 card hunting, though I'm sure those cheerful funny cheeky generous gits are still rocking them at R10 when the mood takes their fancy - anyway, whilst happy to share that, I'm not sure what that perspective signifies in terms of a template for R11+ popularity/incentivisation. The first quest and to a lesser extent the sneaky one of those were pretty challenging, but the other two weren't that tough. They all got run just the same though.
Funnily enough I remember running with the same crew and R10 Ravenloft was tougher, at least relative to the power we had back then. I was learning the R10 ropes and tbh really being carried for a good while until I did, but that's when I recall the game being toughest.
If folks want extra challenge they'll run it for that, I'd reckon, without needing anything exclusive, I would for the helluvit and am pretty sure my guildies would too (I'm absolutely certain the old crew would!) but that's just me. YMMV and all that.