For me, the language of a project has a large impact on whether I would consider contributing to it or not. When I dislike the language, I'll usually not want to be involved with the project, but just watch it growing. Thus, it makes a project more interesting for me if the language is nice.
I know. That’s kind of true for all of us. But yet I believe this is not that important. Specially not important enough to put the language like a badge of honor beside the project’s name or description in the title, like how these “written in Go”s are.
If a projects seems interesting enough for someone, it’s more than easy to see what language is it written in. BTW, that’s how things work: you don’t decide to contribute to a project because it’s written in your favorite language. You first have to like the project itself, and if it happens to be in a language you’re comfortable with, you may contribute to it.
Your last sentence while intuitively seems true, simply isn't. There are plenty reasons some one might contribute to a project, the language could be the only reason, and that would be completely reasonable.
Example: You might not be interested in writing a text editor, but you've seen this and the lime project, both written in Go, you don't care for writing a text editor, but you might figure you could spend some time to this guy fix an issue in your free time.
Is the above a little far-fetched? Maybe, is it unrealistic? Not really.
