Imagine being on Windows, and you don't like the Windows desktop and the way the windows interaction works. Oh wait, you can't really easily download a bunch of windows managers and try them out. But I'm not on Windows, so who cares. Windows users can just let Redmond dictate how they should live their lives...
But on Linux, you often get either Gnome or KDE by default. Those are heavy, bulky, flaky, inflexible, sluggish, and not like the usual Linux spirit at all, in my opinion. Once a upon a time, Gnome wasn't half bad, with Sawfish as it's core windows handler. But now, just like KDE, check to see how much memory things take, and see the extra processes there are in the ps list. Never mind memory, see how long it takes to boot the darn thing. The Gnome terminal has to be the slowest and most inefficient terminal ever conceived. Why on earth announce with icons how the keyboard and mouse is being initialized, wooptydoo. And now that Sawfish was arbitrarily ripped from Gnome just because someone felt like it, in favor of some other way inferior and far less configurable windows handler, there just isn't any point to give Gnome any more attention. And KDE is hardly any better, it suffers from most of the same problems, and has other problems too.
Occasionally, at different work places, when installing Fedora or something similar, I'll work with Gnome and KDE for a bit, but quickly get annoyed with the slow startup time, and annoyed how this Redhat monitor is glued right into it somewhere. My home network firewall is full of port 80 forwarding violations. Then all of a sudden, I'm not allowed to move windows half off the screen along the top anymore, because now all of a sudden the window title bars must be reachable by the the mouse. But I move windows through alt-drag, so why the heck not let me move windows up? Gnome/Sawfish used to have all kinds of options that lets you customize all of these things. But now, it's all of a sudden simplified, and now we're all of a sudden expected to buy into the preferences of the way the author thinks that things should behave. Many shortcuts are gone, and most of the flexibility has been flushed down the toilet. Gnome has been steadily going backwards for the last number of years.
Enough ranting, what to use instead? I've been using IceWM for a number of years now. I've tried a few other ones too, like Twm, Blackbox, even this Rat Poison thing.
What I usually do, is download the latest IceWM source from the CVS repo, apply some home brewed customizations (optional ofcourse), compile, install, slap in an Xclients file to get it started upon boot, and Bob's your Uncle.
Unfortunately, this kind of thing contributes to the fact that Linux is not ready for mainstream desktop. Things are too finicky.
Although - it is possible to install and configure someone's computer. I've installed and customized Linux occassionally on people's computers, after Windows got blown away buy some viruses, spyware, and the like.