Condolences on the rough experience with Castrum Meridianum. The Praetorium dungeon you'll soon also encounter has a very similar format. You will probably find it most enjoyable to do it only with people that you already know are happy with actually watching the cutscenes in proper context. There's even a Party Finder checkbox just for "no cutscene skipping." If you can't get the full eight people that are happy doing it this way, you can also use the option that removes level sync and allows a smaller number of higher-level people to help in exchange for the fights in the dungeon not giving any EXP.

As for rushing - in these two eight-person dungeons or anywhere else, while it is common, it is still not okay. No one has the right to bully you into a speed run. If you speak up and ask them to be patient but they're rude or mean or anything, you can report them to GMs and it's actionable. But, like I said, easier to just avoid the situation in the first place.

And yes, it's just these two dungeons that are like this with lots of story in the middle of the dungeon. =)