I understand what you're saying, and you're right. The most important place to talk about bugs is in the bug reporter. But I don't think the people that discuss and report bugs on this forum have any illusion that this is a good way to reach Apple. It's just water cooler talk to a certain degree, a "you share your bugs and I'll share mine" kind of thing.
The people that truly understand what a beta is don't actually complain about the bugs even if they do talk about them here. Sometimes it seems like people are whining about the bugs when in reality they're just trying to convey the scope of the issue.
All this talk about bugs and missing features and whatnot is pretty much meaningless, but for those who partake in it, there's a degree of fun involved in it. I personally enjoy using beta versions of iOS because it makes me appreciate the finished product so much more. I know what I'm getting myself into, and I know it's my fault if something bad happens to my data or my device. If only *everybody* using iOS 7 now could understand that!