Eh, it could be more casual if not for the fact that the only raid lockout system in Classic is raid IDs, which is what mythic raids use I believe?
If it were per-boss lockouts, there’d be a lot of pug raids in Classic. There will probably be some anyway, but not nearly as many as there’d be if we had per-boss lockouts instead of raid ID’s.
Also, wrangling 40 players to be on and not AFK at the same time is harder than 10-25.
Casual PvP is also not great in vanilla since PvP is very gear-centric and the best gear in the game comes from the last raid. So you either need to no-life PvP for mid-tier gear or do the most difficult raid for the best gear. BfA PvP gearing is also either, be a top rated player, or do mythic raiding/high M+ for the highest ilvl gear (but with titanforging as a maybe you’ll get lucky backup), so both kind of suck compared to TBC through whenever they stopped doing PvP vendors and conq gear. Retail does have ilvl scaling so you’re not as far behind as you would be, but you’re still not on an even footing (and they refuse to even explain or give an exact scale for how BfA ilvl scaling works, which is insane).