i don't even see as a series of "pop-ups" but as a "dynamic bar that opens the necessary sub-options on a click.
And to be clear I think the way Solasta does it leaves a lot of room for improvement as well, both in terms of general aesthetic and in terms of size/position optimization.
But I surely prefer to click "Spell" and have a sub-bar of all my spells arranged for level over having a mishmash of different abilities, spells, ordinary actions and items overcrowding the same elongated hotbar without rhyme or reason and competing for some real estate on it.
I'm not good with Photoshop otherwise I'd love to make some mock-up of how that would ideally work in BG3, even keeping a lot of the same aesthetic but rearranging entirely how the sub-menu (that fundamentally are already there as "tabs") would present themselves more fluidly.
I also thought Solasta would have benefited greatly from HOTKEYS!!!! But yeah. It needed to not be so huge and taking over a third of the screen. Not necessary at all.