This happens to every OS update. Remember when Leopard -> Snow Leopard and people were complaining about some problem with the OS.
Reality is it's going to be split 50/50, half will have no problems upgrading to Lion while the other half won't do it for whatever reason. With the threads you linked to, the problems with those users were stability and driver problems that Apple could fix with updates. Some of the problems/annoyances that people are having in this forum with Lion are dropping PowerPC support, poor RAM management, Mission Control/Expose.
With dropping PowerPC support, as a user, there's nothing you can do. Apple has moved on, you either stick to what you have or move on and purchase supported software/hardware.
RAM management, this is something Apple can improve on in the future with OS updates.
Mission Control/Expose. This is an added feature that Apple probably won't change, so to the user if you want to upgrade, you'll have to deal with it and learn to adapt to it and it's shortcomings.
I get your point though, there's always going to be a group of people who complain but with those complaints you posted, it's not stuff that Apple added it was just early drivers that can be addressed. From the people complaining, it's due to things that Apple has changed and added and depending the user, it might or might not be for the best which is why you're upgrading or staying with Snow Leopard.