If you're interested in a much richer type system, but also like the actor model, check out Pony (http://www.ponylang.org/), which has some pretty seriously great goals.
That said, I think the theory was that dialyzer's success typing was the most industrially pragmatically acceptable type system available at the time -- the one that you could actually get people to use -- and given all that, it's not half bad. Certainly better than nothing.
Yeah, Pony looks very cool. Unfortunately I don't think I could convince work to use it at this early stage, but I'm looking forward to see how it develops. Huge bonus points for being based on soundness proofs from the very start.
Yeah, Dialyzer is better than nothing. I guess I get saddened by the lack of parametric polymorphism due to being spoiled by Rust and Haskell, and have been sceptical due to noticing that type inference sometimes falls back to the top type without me realizing. Kind of hard to trust a type system to have your back after that.
Yeah, I gave up relying on type inferencing; at minimum I add type annotations to every exported function in a module, and every function that calls out to an external resource (i.e., a function that reads from an external database, I'd declare what is returned).
That said, I think the theory was that dialyzer's success typing was the most industrially pragmatically acceptable type system available at the time -- the one that you could actually get people to use -- and given all that, it's not half bad. Certainly better than nothing.