I think the current system is already more complicated than it needs to be, and rather than trying to balance hosts and joiners they should get avoid the polarisation.

Presumably getherwings was introduced to incentivise Co-Op. Not sure how necessary this is right now. But it could be a problem in the future when players are powerful enough to just solo even top-end content. At the least wings gives Cygames an adjustable mechanism to promote or discourage more Co-Op for whatever reasons. So in lieu of of a completely new incentive scheme, which would take more dev time, I think they should keep wings, but make the following changes:

• Allow you to spend Getherwings for hosting or joining.
• Once you run low/out of getherwings, you can use Stamina. That means people who don't usually like Co-Op are still incentivised, and players that really enjoy it can keep going.
• Now that hosts and joiners are on the same 'currency', lets just get rid of this grouping for PUGs. Players join queues for quests, and a room is started by popping 4 players off the queue, straight into it. The first person popped can take the role of Host, deciding when to start the game, and whatever technical duties are needed from hosts. From there the room should work like currently.
• Private rooms can continue to work as now, just that the host spends wings first, then stamina. Or if Cygames really wants, they can leave private hosting as stamina only (if they're worried about keeping PUGs populated).

(Ok, the first bullet point was just to show the thought process).

This gets rid of having to balance the Getherwing economy, players still can afford at least as many Co-Op games as the current system, and still have to participate in at least as many if they don't want to lose out.

Its possible this end up with less Stamina going into the Co-Op economy than currently (so possibly less games overall), but I think any loss from Host stamina will be at least somewhat offset by the people wanting to play Co-Op more, playing more. Not to mention it would be easier to get games going. The other big loss I think is, since you can't choose to host a PUG, it makes it harder when you want to be choosy about Party makeup. But maybe you shouldn't PUG for those anyway. Or Cygames can include an option to always host, but be forced back to stamina.