New languages can outweigh low popularity with lots of other important qualities: syntax, tooling, appropriateness for a certain purpose, abundance of libraries, etc. If the new language is easy to learn, that pretty much defeats the issue of low popularity all together!

Unfortunately, a lot of new/amazing languages with great tooling are somewhat hard to learn. Again, Haskell might be a great language, but it's daunting to people who only have experience with C-like languages.

Go is one of the exceptions, and I think it did that intentionally. Instead of having complex syntax, it just has lots of boilerplate. It's easier to read and easier to learn at the expense of being harder to write and harder to modify.