Stupid space wasters that make everything look like a toy.
A professional taskbar should be attached to the bottom of the screen, and an unprofessional one should be auto hidden or on the side of the screen. Top’s a bit weird, but has character.
I moved from Mint to Bazzite the other day and was just about ready to move back when I saw the default desktop. Flatpaks are… Different, but don’t seem particularly better or worse yet. That fucking floating taskbar had to go though. Disgusting. Stick to the edge of the screen like you’re meant to.

Its where GNOME heretics go to be buried in 10,000 checkboxes and layers of customization options and small clickable areas. /joke
No reason, any kernel filesystem should support saturating a disk drive. You can use BTRFS if you specifically want compression, subvolumes and features like btrfs send/receive but real world performance for games will not observably change.