You should define casual players. To me casual players are people that play a few hours a week (maybe up until 5, maybe 7), and have a lot of content they have not touched (like exploratory zones, for examples), and a backlog they will probably never complete. Those people have probably not seen any problem.

Problems come for players that play more and don't raid or go into high lvl content. They've probably engaged (maybe finished) most of the content. That's the public for which exploratory zone lacks.But those people can't really be called casuals anymore, despite often being grouped with them. Which lead to those situation where some says "it's bad for casuals, then a real casual comes and just say no. It's for those players (more midcore thus) the extension has been awful. If they don't raid, don't engage in very hardcore farming rewards, everything has been one off and they have no reason to do anything in the game right now. It has been a little better for hardcore players because of the raids, but long running content is also done by hardcore players, and they also felt it.

Casual to Hardcore player is not a two pole thing, but a spectrum, and I feel like a lot of the problem in EW are due to not seeing it like that, thus ignoring the whole middle of the spectrum. And this kind of thread participate to that problem.