In the short term, GNOME's gradualism seems sensible. It doesn't confuse users, and it doesn't accumulate bad reviews from writers with an aversion to change. But, in the long-term, it could very well mean continuing to be dragged down by support for legacy sub-systems. It means being reduced to an imitator rather than innovator.
By contrast, you could say that KDE has done what's necessary and ripped the bandage off the scab. In the short term, the result has been a lot of screaming, but, in the long-term, it has done what was necessary to thrive.
This prediction does not mean that KDE managed the release of 4.0 well. If anything, from a management perspective, the project bungled the release -- especially since reviews of beta releases should have provided clues about what the reactions could be.
A transition guide, and clearer communication to distributions that 4.0 was not intended for the average user, might have eliminated many of the complaints. But how the project dealt with expectations has nothing to do with the software engineering.
Nor am I suggesting that every change in the KDE 4.0 releases was a successful one. Personally, I have nursed a grievance against the default Kickoff menu since I first saw it in an early beta. But experiments by definition are not always successful.
Considering that alternatives are available, who cares about a few failures? The chances are, they cost less in terms of usability and developers' time than maintaining continuity with the past at all costs.
In all the controversies -- both the real ones and those imagined by journalists -- what has been lost is the exact nature of what KDE has been doing. When the free desktop quietly came to match the functionality of its rivals, the GNOME team decided to be content with maintenance and minor additions. However, the KDE team decided to try to take the lead in desktop development. KDE became a project with vision -- a vision that has gone largely unnoticed, but one that GNOME so far has been unable to match.
It is this vision, as flawed as it sometimes seems, that gives KDE the evolutionary advantage for the next few years. Far from reducing KDE's competitiveness, as Jack Wallen suggests, the 4.x series may be exactly what the desktop needs to restore its market share.