as much as I'd like two screens for the sake of video editing, my room is just too tiny to have another monitor. I only have a tiny desk, and it fits my PS4, Wii U, monitor, and external speakers.
See, I had the same thought as you-- who needs more than one monitor? It seemed excessive to me. But at work, I have 2 monitors. It's great, because I can put my web browser and email on one side, and our point of sale software up on the other, and then I can copy and paste part numbers from the browser into the software without clicking back and forth! Having everything spread out nicely on 2 screens is actually kind of nice, now that I have it for 8 hours a day, lol. Just think, WoW open on one, Elitist Jerks (or whichever DPS gear guide is best this week) open on the other. Perfection!
I think one or two screens would be okay for a good gaming feel. Too many screens may go some way to complicated your experience.
All my activities revolve around my laptop and I've connected two display outputs to my windows laptop. It works best for gaming, movies, programming, TV and others.
I currently have just one monitor, but I would really love to have at least two monitors. I do think I could use two monitors if I am going to do live streams while playing.
Really, at the moment I have one screen but I plan on updating and perhaps getting a new one in the future.