Because the Steam client tells the window manager not to decorate its windows, I'm missing various options like send-to-back, shade, move to workspace, show in all workspaces…

Because it uses its own window decorations, clicking in the wrong place can initiate a mouse drag. I quite often accidentally resize or move the window by a small amount because I happened to miss the button by a pixel or two.

Because of both, it doesn't properly fit in on my desktop.