Years of XMonad use here. Really, it's not the interference you are imagining.
Much of the time I have a web browser using a whole portrait-aligned monitor, but sometimes I feel like having it 2-up in a landscape monitor.
The win of nice clean window separation, without giving up significant percentage of my display space to window decoration, is -profound-.
I have one pixel borders around my shells, and I have it because I fiddled with zero and decided I liked one better. How many pixels do you lose to decoration, so you can mouse over them cleanly? That's a major win.