We started building some services in F#, but still had a massive amount of C# - and so I wanted the inertia of my team to be in the direction of writing declarative code. There wasn't really anything (outside of LINQ) that did that, so I set about creating something.
We don't write F# any more and find functional C# (along with the brilliant C# tooling) to be very effective for us (although we also now use PureScript and Haskell).
I do have a stock wiki post on the repo for this though [1]. You might not be surprised to hear it isn't the first time I've been asked this :)
[1] https://github.com/louthy/language-ext/wiki/%22Why-don't-you...
That post in the wiki sums it up perfectly, much appreciated!