It's a feel thing. I have two screens, with a minimalistic bar taking about 15 pixels on the top side of the secondary monitor. No opened apps or anything displayed there, to see that I'll just press Alt tab or the plasma overview (very gnome-like). That feels less cluttered than a bar that, to have the floating effect, steals me more vertical space than what I have.
This is very personal so it's nice that KDE let's us do whatever we want. IDK about the default choices as long as they let us change it to whatever we like, so I don't really care.
I just deafen the complaints of tm friends and break the tether every time.
PS: as a lemmy geeky user, every time means like once or twice.