One of the features of Ruby is simplicity. In that case, more features will usually mean less simple. The feature of Java and C++ is features, so the way for them to stay relevant is more features.
I have used ruby for a long time so 99% of it makes sense to me, but it definitely is _not_ simple.
Still, some increase in complexity may be acceptable: we have limited destructuring and case equality, pattern matching would be just a bit better. We have `Struct` which creates classes with positional arguments, but not a version that takes required parame even if it's a natural extension. We might have better composability for mixins etc..
And we can keep removing things (some more perlisms, for one).
I am not sure that is true.
Many of the "old" languages that are still successful seem to have changed over time, while most of those that have stayed mostly unchanged seem to have lost mindshare (even if they had most things to begin with). It is probably a marketing problem.