Works both ways really, people might hate your project because you stick to old & known C, rather than write it in e.g. Go.
What matters is what's most productive for the project, for the people working on it.
What doesn't help is making a fuss about it. Spend your time contributing and get over the fact that not everyone thinks the same. Or walk away, because nobody is forcing anyone to get involved.
Let's just stay constructive and respect what people are doing.
If you really want to do it differently, just go out and do it, prove people wrong with results, rather than arguments and flames. That way everyone wins.
Is C inherently unmaintainable in your opinion? Or just badly written C?