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.

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