I personally find that movable-window designs are a UI failure, requiring too much user interaction. A tiling WM, OTOH, enables me to do what I want: work with one tool or another, and work with multiple tools when that's what I want (which, frankly, is rarely — other than consulting a browser or info window, it's not often that I need more than one window on my screen at a time.

I think people often forget: Do what works for you. If XFCE+ is good enough for you, then great! stick with it!

But if you want to try a different experience, or if you think that setup is inefficient (as I do), then try moving to something else!

What works for one person likely won't work for another.

And this is what killed the Linux desktop. 99% of the population does NOT want to try a gazillion desktops (of which the installation is error prone), just to find out what 'works best for you'.

You don't have to if you don't want to. Any sensible desktop distro has a DE configured for you out of the box, if you want to just start using it.

For me it's because a tiling WM is simpler, more aesthetic and more responsive.