Extensions have a great number of problems, the updating issue is only one of them. And I still haven't had anyone explain how extensions for preferences is in any way preferable to a damn checkbox. Honestly I don't think KDE has too many options, it has too few. But then again I stopped using it after 3.5 so I guess I don't know how it looked after 4.3 or 4.4. I certainly will not argue that KDE 4 is also a UI disaster. More generally, option clutter can be managed and with advanced tabs, hid. I also don't think everything needs to be an option, but there are a couple of dozen common sense options that would barely increase the clutter and made the thing more usable and more palatable.
Similar to you, the alt-tab default is certainly a poor choice for me. Moreover, I am not going to install a random beta extension to "fix" it. By the time I would have enough extensions installed to make the desktop fit me, I am bound to have interaction issues, slow downs, etc. And hunting through a flat website to play wack-a-mole to find all the extensions would waste more than enough time, thanks.