Glad you brought this up. It feels, at least to me, like FUSE is only for...hmm...gimmick or science-fare projects. Maybe something useful on your development machine. Indeed, at a previous employer, several problems were addressed using a handful of FUSE filesystems, quite elegantly. Of course the caveat was "this ain't prod, duh, it's FUSE". But this doesn't NEED to be the case. Tangentially, microkernels pop up here often, and arguable, moving some filesystems to user space makes sense in a related vein.
I'll admit, I'm all talk and if it really mattered, pull requests are probably welcome.