The funny thing about your comment is that you could have made the exact comment in 1995 to dismiss Java. Sometimes it just takes very long for ideas to reach mainstream, but they can nevertheless become extremely successful.
The most important innovation in the Hindley-Milner type system was parametric polymorphism, since that is the thing that enables you to build more powerful abstractions. Since the release of Java 1.5 and C# 2.0 that is now fully mainstream, but it took more than 25 years.
Oh, I have nothing against new ideas in programming languages, and I think the more "researchy" programming languages are invaluable to the community in the insights they provide on what works and what doesn't. I was simply responding to the befuddlement that the industry prefers languages that adapt ideas slowly, rather than those that are cutting-edge.
The most important innovation in the Hindley-Milner type system was parametric polymorphism, since that is the thing that enables you to build more powerful abstractions. Since the release of Java 1.5 and C# 2.0 that is now fully mainstream, but it took more than 25 years.