Honestly I think that SE simply needs to make PotD / HoH DF'able. It wouldn't be difficult for match groups to start with certain 'base' Pomander counts above a certain floor level, so as to make it somewhat doable.

Personally I love the idea of fixed parties, but FFXIV just isn't built for it. Unlike FFXI, where fixed parties were a necessity to do... well, more or less anything outside of basic leveling, in XIV, they're almost never needed. End-game raiding and these Deep Dungeons, maybe Rathalos EX. That's about it. As a result, the average player simply doesn't have the right mindset for static parties. You can't take a casual game that's designed for people to play at their convenience 99% of the time, and then expect them to be highly accountable to others for the remaining 1%.

With Savage and Ultimate fights and such, it's arguable that there's simply no replacing the static element there. Those fights have a style of difficulty where you have to learn as a group to succeed for the most part. The Deep Dungeons, though? There's nothing special for that beyond being highly attentive and tactical in how you engage groups. People can pull that off in a matched group, and so SE should allow for it. Matched groups should only be restricted when absolutely necessary.