Right, no objections if that makes things better for you. I would like to mention that in Plasma Netbook (the netbook-optimized edition of our workspace) we've tried a sort of alternative approach where if windows maximize, we disable the borders and merge the window controls into the top panel, to achieve the space saving. You can also set that up in Plasma Desktop of course.
As for app menu in a panel: That's actually something we had back in KDE 3.x but are still lacking in the KDE 4 mainline at present, mainly because it's taken a while to coordinate the standard with folks like Canonical and because we really wanted the core patches to be integrated at the Qt level. Things look to be coming together now for the upcoming 4.9 release, though I believe (K)Ubuntu has actually been shipping the patches for a while already, for the benefit of KDE apps running in Unity, but also to support the same sort of arrangement in KDE workspaces.
As for CSDs, there's bunch of other things they break that I didn't list in the original post. For example, with WM-provided decos, the window manager can detect when you're trying to interact with a frozen app and offer to kill it, which is in fact something we're doing. If you move the deco into the app process, though, well, then it hangs together with the app, and things get a little more complicated. And there's performance issues in some remote desktop cases, and so on.
