Argus could've had very different-looking zones with all sorts of creatures, just like the Broken Isles aren't all about demons. It never made sense to me that the Legion destroyed Argus like that, because even though that's kinda what the Legion does, they also still have to use the planet as a basis. Now it makes sense to fel it up a bit here and there, but why would they break the planet apart like that? What's the sense in that? That's less land to stand on. Less land for your troops. Anyway, they could've easily splintered it apart like they did with Outland, and therefore preserve some of the zones in a way that they used to look like before the Legion came. Apparently that kinda is what Mac'Aree is like, so why not just do that with 3-4 more zones, add 1-2 fel zones into the mix, call that an expansion. Yes, another demon expansion would've been alright, if it had elements like in Legion with the Vrykul, the Drogbar, the Nightborne and Nightfallen etc. Things that relate to the Legion while still offering some variety. Hell, if you quest through the 5 normal zones of the Broken Isles, you barely feel a Legion presence. For Argus they could've added Ethereals into the mix, maybe some zone with a group of these Holy Nathrezim, new creatures they invented etc.