I doubt they would feel sad about their technology being adopted by a mainstream language used by millions of developers vs. a research experimental language that many outside of research haven't even heard of before.

wasnt smalltalk once a mainstream language? in ancient times, late 80s?

The number of programmers back then was much less than now, but even then I don't think Smalltalk was a top 10 language. I guess it depends on how you define mainstream, Smalltalk has/had its niches, some of which are still active. But there is nothing wrong with using research languages like self (which was never mainstream) to explore and develop new tech that can be applied to mainstream languages.

Presumably some of that effort is responsible for the JVM begin chosen to host other languages.

Java brought garbage collection into the mainstream. That alone is enough to consider it progressive.

Any big company with that kind of money and connections can bring pretty much anything into the mainstream, not a big merit IMHO...

I've always wondered that about Guy Steele. Must've been an awfully well-paid job.