Like the one guy in the comments stated, I also wouldn't have it installed if it weren't for a couple of programs that require it - and I have completely removed it before since it went corrupt on my system and reinstalled it clean which was better than the "recommended instructions" of formatting Windows.
Not being a techie myself I have no idea why .NET was needed. Just seemed like a way to hide a lot of bloat.
it allows programs which are written in .net to not have to bundle the entire library in themselves basically the same as the MS visual C (but different languages). I believe the .net language also allows the programs to better interact with windows itself.
That's the point. I think the whole idea of .NET was to bury the unknown bulk of other necessary Windows programs (other than MS visual C, and anything else related) (more about telemetry, telephony, GPS, etc.) into an un-assumed 3rd-party-esque non-app. The bulk of the population didn't know what it was for. They didn't need to know. It worked, but nobody (like me) knew what it was for.
But then again, it's almost Christmas. And Merry Christmas to Nergal because you have the fantastic Grinch as your avatar.