"the number being bigger made me stop holding it in my head" is a bad thing.
The issue comes with that once I stop holding those numbers in my head is the moment when I stop caring about those numbers. And, considering those numbers are, like, one third of the entire game (Planet management), that is a pretty bad sign.
It used to be that the early game was held up by exploration, planet management, expansion, and economy.
Now Planet management is just a grey blob (the pop numbers are too large to effectively recall, and thus hard to care about), economy is trivial (and thus uninteresting), and expansion is glacial because new Colonies take decades to become even mildly interesting even with manual forced pop relocation.
That leaves the exploration as the only somewhat interesting thing remaining.
Sure, I could go into a War. But that is only a temporary distraction, because the AI basically just rams their biggest Fleet into mine with little regard of whether they can actually win or not. So it is not like the AI is making anything even mildly resembling smart moves. Hell, sometimes they do not even feel like repairing their Fleets.
So, yeah, maybe collapsing three of the four pillars that made the game interesting was not exactly a stellar decision. The Pop UI was one of them, and the Pop rework is related to all three of them.