Is there a dedicated place for official feature request submissions for KDE products?

it seems wrong, to me, to submit them to the bugtracker.

You could do that. There is a wishlist option under the "Severity" drop-down selector. But , as you can imagine, what one person wants ranks pretty low when it comes to severity, so more severe bugs will tend to take precedence.

But, know this: KDE is not a a company with a suggestion box. it is an open-ended, grassroots, volunteer-based community with undefined, permeable edges. This means you can become part of it. If you want something, you should become part of it and contribute to making it happen.

If you don't know how to code, or think you have nothing to contribute, do not underestimate yourself: you definitely have something that can help KDE. And, even if you end up contributing to something that has little to do with what you want done, you will be helping, however indirectly, to making your wish happen.

So hop in!

The bug tracker is the correct place.

The ‘Help → About KDE → Report Bugs or Wishes’ dialog available in most KDE applications ends with this paragraph:

If you have a suggestion for improvement then you are welcome to use the bug tracking system to register your wish. Make sure you use the severity called "Wishlist".