As a genre, conferences presentations suck. There are myriad reasons why, but the bottom line is that it doesn't take a little more effort to go from a meh presentation/conference to a great one. It takes three, four, five times as much effort -- that is assuming that you've got something interesting to say at all.
Either way, for most people it is simply not worth the extra effort. They're giving presentations because they're good at doing something, not necessarily talking about it. It would be, objectively, a mis-allocation of the time of the vast majority of humanity to bother coming up with really good conference talks. That time is better spent elsewhere, unless you're a salesman. Wishing for better conference talks is like wishing for more industrious workers for your collective farm. It just isn't going to happen.
It is particularly disheartening that education conferences suck as much as all others. One would imagine that teachers would be inherently good at this, but consider the opposite. Would people who give good conference talks always be good schoolteachers?
Unconferences are a good way of compensating for the fact that conference presentations suck.
What I completely don't get is the virtual conference, or the internet broadcast of typically crappy real-world conferences.