what apple should do is a permanent fix, bumpers imho are not hopefully the new batches are better.
You're right about the bumpers. When I was watching during the meeting, I thought "why are they including these? They don't make sense since they're not big enough to protect anything?" Of course, the answer showed up a little later, but just for a few, very vocal people.
It's really as simple as putting some sort of lacquer on the antenna at that contact area. It won't cause significant signal degradation by itself and it will keep the antenna out of direct physical contact.