Up to just a few years ago, I couldn't wait to update all of my devices to the latest version of whatever firmware or OS was released. Lately, most 1.0s are treated as alphas and filled with bugs. This behavior of turning your customers into free testers is disgusting since those companies are not one man shops or indie developers where you could understand the reason why something like this happens. They all have fully staffed QA teams. Because of that, I'm certain that it is not the fault of the developers or the QA teams, it is just a decision from high up to release on that date, no matter how poor the experience will be. I'd much rather have a delayed launch date than a buggy OS that is a pain to use.
Another cause is the will to keep pushing out new major version of each OS every single year. If they could keep up with the realize cycle it would be great. It is clear that Apple cannot keep up. They either, as we've all been saying for years, make a bug fixing release like Snow Leopard, on just drop this an OS a year self-inflicted tradition.