Immersion and more screen space. I have an ultrawide monitor (3440 x 1440) and I would never consider going back to more traditional sizes. The monitor posted seems excessive but if I had the cash I would consider it.
https://www.youtube.com/watch?v=eDyXIXyAZq0
Please consider adopting a cat from your SPCA or local animal shelter.
There are plenty of reasons to use one. If your into Racing sims, or want something different for WoW, this is for you. If your an architect, all that extra space is awesome. And I'm sure there are addons that will allow you to split up the screen into smaller screens.
So how would watching a movie look on something like this?
Probably pretty good? It's like a screen in a movie theater, just instead of really big and far away, it's much smaller (relatively speaking) and up close.