Like Claire said, everyone still needs to learn the mechanics. I'm not saying this to come off as an elitist or a douchebag or anything but once you know the song and dance of fights like ex primals they're dirt simple. That's a big factor in why weekly clear parties usually demand people with experience since you can clear them reliably on the first or second attempt with people who know the fights, regardless of ilvl for the most part.

I think the real issue here is that instanced, mechanics based combat just isn't casual friendly. In contrast, iin FFXI, virtually all content could be done by as many people as you wanted to bring. More casual group? Hell, bring a friggin army and have fun with your friends. Hard core? Low-man ftw. That kind of system also meant that your gear and skill both played very important roles. In XIV, a DPS, for example, who's mediocre at their job but amazing at dodging mechanics is better than the best DPS in the world if they can't dodge. Sadly, this means the only way to make mechanics driven endgame content more "casual friendly" is to increasingly nerf the absolute crap out of it. I think even casuals can agree they'd like a sense of accomplishment when they finish something.