One powerful GUI toolkit available from early version would save Windows' GUI consistency and work of all platform developers.

I like Vista, but things like this really bring the user experience down, because of inconsistency.

I noticed, that on Linux, it is mostly solved by having universal GUI toolkits (GTK and QT), and that way, application's look and feel is always consistent, and it is possible to update the look of an app simply by replacing toolkit's files in a system.

On the windows platform, however, apps are directly acessing windows API and implementing their menus and other GUI parts, and without an intermediate layer of GUI framework, they need to be rewritten to be updated to a new look.

And that is the problem of Vista leading to a sites like Long Zheng's UX Taskforce - apparently, there is a lot of programming teams in MS, and each one has a bit different opinion as to how interface should look. This is nothing unexpected - try to synchronize aesthetical feelings of several thousand developers - but it is unnecessary, and it shows that more is less. If there was only one way to do menu, abstracted from look, things would be easier on both sides - look, windows, here is a hierarchical structure with menu items, shortcuts, icons and callbacks, and now draw it as you like, in a manner consistent with a platform.

Another thing - layout: QT and GTK have a nice layout support, so it is possible to just stack some layout placeholders, and have everything resized automatically, even when window size/dpi/font height/ammount of text changes. In pure windows API, this needs to be coded by hand, and if everyone does it on his own, everyone will do it differently (and everyone will forget some edge case when things will get broken).

OK, there appeared some GUI frameworks that solve this, but still, each one of them do things differently, so it is still much worse, compared to situation when windows would have a powerful GUI tookit from the beginning.
So, sorry MS, but you are the cause of inconsistencies, which bring you laughter from both apple and linux fanboys (and cost you millions on maintenance costs with every new version of windows), and being a Vista fan, I must agree with them - sadly, though.

On the other side - making the platform developers sprinkle their code with unportable windows API constructions is maybe the best way to ensure that code won't get ported to competing platform. But if there was an evil mastermind behind it, it caused a huge pain to every windows developer. How sad :/.

PS: Of course, now with .NET System.Forms and WPF, things are much better, and easily maintainable, but so far, 99% of applications in Vista installation are native, written in C++ and Windows API.