> the languages are significantly simpler than Haskell
I don't think that's quite true.
Ocaml has plenty of advanced features (the module system, GADT, structural typing in the object system) but the community relationship with them is very different than how the Haskell community uses the language. For the most part, the Ocaml community tends to dislike gratuitous complexity and be non dogmatic (I fondly remember a lens library announcement on which the top comment could be boiled down to "just use mutations").
> My only gripe with them is that there seems to be a culture of having zero type annotations (due to HM), which can make reading other people's code difficult.
Interfaces tend to be annotated (mli files) but usually people rely on the tooling to know types inside files. Merlin is a blessing. It is a very fast type-checker which keeps working on incorrect files.