What is it you don't like about OCaml, or similar ML-family languages (e.g. F#)? Most of "modern language design" seems to amount to the ML featureset.
No multicore
Standard library has... issues
No community consensus on a common base setup, questions about which library to use for a task often get answers like "well, do you want to use functors or monads? because that will change the library we recommend" which is really not what you want to hear when you're just trying to set up your first server.
Documentation is, in general, bad. Most packages just give a list of function signatures.
The community is small, academic, and often French.
Anyway, there is no way you'd give up ML-tradition pattern-matching; D doesn't have it.
If OCAML were already popular I don't think the lack of parallelism would be huge issue, but it's niche, which is a huge downside to any language in a business context. The upsides the language provides in terms of performance, ergonomics, and maintainability need to overcome that downside. All the issues I listed mean that OCAML can't generally pass that bar.
OCaml: multicore, standard library situation (which one?) is a mess, adoption. F#: Have to deal with null and lack of ADTs when you interact with .NET (or JS for Fable) standard lib. The tooling situation in F# has been a mess since .NET Core, especially in Linux. Treated as a 2nd class citizen by MS.
The other issue with the package ecosystem is cross-platform support. While OCaml itself works on windows, opam doesn't (or at least didn't) without a lot of extra work, and it seemed like most packages were designed only for unixish OS's.
There are projects where I've used Rust instead of OCaml, even though I'd have preferred to use OCaml, simply because the infrastructure is so much better and easier to use for Rust.