I remember this same "rise in popularity" in 2005. Every few years functional advocates get all excited (last time was F# support in Visual Studio, all C# programmers were going to switch, naturally).
I suspect the reality is a small subset of programmers think functional programming is amazing and everyone else hates it. You might think it reduces complexity, but a lot of people feel it reduces comprehensibility.
> I suspect the reality is a small subset of programmers think functional programming is amazing and everyone else hates it.
Yep. It's not that I hate it, I just don't like it. The thing is that the functional-praisers are much more vocal about how they love it whereas people who write imperative do not care much about Haskell.
We are happy with LINQ and that's all 99% of us wants/needs.
