Some of the games I play are huge and with Series X|S optimized upgrades they're even bigger. Setting up the Series X and copying games over from my existing Xbox One X highlighted the issue. But I folded basically the same day my Series X arrived. I promised myself I wouldn't do it, I'd simply make do and copy games across from a USB 3.0 HDD as and when needed. Ultimately the lack of internal storage options is what leads to the decision of even considering one of these. And the Series S can be filled with only a small handful of games. If there was a 2TB model of the Series X that cost $100 more, I know I'd have happily splashed out the extra as I'm sure a lot of folks would. Sure, SSD storage is more expensive to use than the crusty old HDDs we've been using to this point, but what we have to choose from still isn't a lot.
My only major criticism of both the Xbox Series X and Series S are the storage options.