It's not useless at all. I've had Apple respond to me for issues many times in the past and actually saw changes in following releases. If they never respond to your feedback that means they either cant replicate (if they cant, they will ask to show how to get that issue via screenshots/video) it or its a common feedback and they will fix it.
That's the whole point of the Beta's, for people to submit feedback. I've even had Tim Cook's and Steve Job's offices reply to me via email for major issues.
Complaining only here on a forum will get you nowhere.