Meta isn't rep gaining. Never has been never should be.
The point of voting tends to be to show agreement or disagreement with a given thread or answer. There are many "make a collective decision" threads which exist and then general agreement or disagreement can be met through voting or such. That's the purpose really for votes on meta.
For feature requests it's the same general thing, in my opinion.
Meta should not affect your rep, either, in my opinion. It's a site about the main site. I think you should only gain rep for contributing to the main site, not contributing to a site about the main site.
If you really care, there's badges which you can earn for contributing here. However, your reputation should only be gained by contributions to the actual main site. Not meta.