Specifically things like instanced 5 man dungeons (like Ragefire Chasm or the Deadmines in WoW) which are explicitly designed to challenge a full party of a certain level range. Notably, not endgame content. I'm sure the answer changes based on different factors (e.g. how good are the rewards? What are the drop rates like? Are similar rewards available elsewhere? How long is the dungeon? Am I late picking the kids up from soccer practice?), but I'm curious what folks' thoughts are. I'm personally sour on the idea, but I understand that my attitude is "the less MMO an MMORPG can be, the happier I am", so MMO designers should probably disregard my opinion.
Supplementary Context: usually about once a year, I get the bug to hop into an MMO. However, I am not a good MMO player. I tend to flit around my gaming library like an ADHD pixie on cocaine, and there's no telling how long my interest will sustain itself. Therefore, any "meta" choice I make is purely by accident, and I don't spare even a moment of thought on "efficiency". In fact, I've often thought of my dalliances in MMOs as digital tourism. By and large, I'm there to craft, read quest dialogs, and poke around in the weird corners of the map for a couple weeks before logging off for another few years. Anytime I've ever done group content (which is, admittedly, not often), I'm desperately trying to keep up while someone nukes everything in the dungeon as they sprint towards the end. I wind up feeling like my lackadaisical approach is probably fucking up someone else's farming loop. Now, I don't think either the sweatlords or I are playing the game "wrong" so to speak, but our priorities are in conflict. Maybe I'm letting people-pleasing anxiety get the best of me, but I feel like the person that cares enough to grind a dungeon reward as fast as possible should get right of way over my happy ass who will intentionally sandbag my way through a dungeon if the vibes are right. Therefore, I tend not to engage with such content, if it's not possible to solo.
This has all come to a head because my current preoccupation is Star Wars The Old Republic. Given this game's much greater emphasis on story and dialog than a typical MMO, I actually feel like there's RP content that I want to see in the dungeons, irrespective of any item reward. To the game's credit, many of these can be done solo by selecting the "story" difficulty option before loading in, but not all of them. I just don't want to be the asshole holding up the party cause I want to watch the 3 minute into cutscene (or whatever) while everyone else is hammering their skip buttons trying to get to the boss.
Not necessarily asking for advice, as the solution seems obvious to me (it's "talk to your fellow players", like it always is), but I thought this might foster some discussion, especially from old heads who might have lived the raid life back in the day, but now have different priorities.

That's the type of content I enjoy the most. Lately MMOs have been drowning in solo content and while it doesn't "hurt" me in any way, it also does not interest me in the slightest, so I end up losing interest.
The few MMOs I played have normal/easy/exploration versions of group content instances, where it's generally expected to be slower and at the very least do the quest and watch cutscenes. I do those up until I'm comfortable with the layout and mechanics and move on. When I encounter people doing the quests in harder instances I do get mildly annoyed, but depending on what exactly is it I can slow down to give them time to click through the dialogue options. If they state beforehand that they are doing something extra or they want to go for a secret/achievement that's usually out of the way, I'm almost always down.
Just set your expectations right before dipping into any group content. If the instance is expected to be easy and is even designed specifically for low power players then it's entirely your prerogative to take it as slow as you want, do the quests, watch the cutscenes, and anyone who is rushing it is the one ruining the experience. If the instance is clearly going to be difficult then don't pug it, find your own group that wants to learn it or look up the mechs beforehand if you don't mind that (I know I hate looking up tutorials myself).
Nowadays there are also so many casual chill guilds in MMOs that specifically gather players who play 2h a week, go very slow, help out with all sorts of content and such, try to look for and join one.
The only aspect of group content I dislike is the potential of future lockout due to extremely low engagement. In those cases games must keep some incentives for all sorts of players to continue replaying old content regardless of whether or not they need anything from that specific instance.