That pattern has a really obvious driving principle behind it. It's not just "every other release sucks."
That can be seen by realizing that vista and 7 are basically the same OS. What happened is that they fixed the poop in vista people hated, released it FREE TO USE for a year, and let people test 7, giving people a full year to port drivers, software to it, and get used to it. During that period, they did shitloads of bugfixes, they took advice and what people liked and disliked into consideration for the RTM. THATS what turned vista into 7.
If they don't release a half-baked operating system in windows 8, they'll be fine. If it's going to come out in 2012, it's most likely not going to be good. It'll need to be at least 2014. There are some areas they really need to work on, and one of those is completely revamping explorer.exe. It's better in 7 than in XP but its still poop. There are plenty of things to improve, and if they improved them all and added further optimizations and improvements to the kernel, it could be awesome.
One thing I'd really like to see added are the equivalent of 'tmpfs' mounts in linux. Basically you take a chunk of your memory and the system treats it like a local directory, files written to and read from it are actually stored in memory.