Andrew Morton has also argued against throttling:

If we simply throttled things, people would spend more time watching the shopping channel while merging smaller amounts of the same old crap.

Kernel developers are, of course, known to be hard-core shoppers, so giving them more opportunity to pursue that activity is probably not the best idea. Seriously, though: Andrew is in favor of a slower development process, but only when approached from a different angle: his point is that an increased focus on quality will, as a side effect, result in slower development. Kernel developers need to be focused on finding and fixing bugs rather than creating new ones and/or shopping.

It is worth noting that a substantial portion of the development community appears to believe that there are no real problems in this regard. Bugs are being found and fixed at a high rate and the kernel is solid for most users. Arjan van de Ven notes:

Are we doing worse on quality? My (subjective) opinion is that we are doing better than last year. We are focused more on quality. We are fixing the bugs that people hit most. We are fixing most of the regressions (yes, not all). Subsystems are seeing flat or lower bugcounts/bugrates.

Ted Ts'o points out that a lot of problems result from obscure and low-quality hardware, and that it's not possible to make everybody happy. Andrew is unconvinced, though, and seems to fear that the kernel is declining in quality.

In a sense, though, that part of the discussion is moot. Nobody would argue against the idea that fewer bugs is a worthy goal, regardless of whether one believes that the current process has quality problems. So talk of ways to make things better is always on-topic.

Testing remains a big issue; the kernel, more than almost any other project, is highly sensitive to the systems on which it is run. Many problems (arguably the majority of them) are related to specific hardware, or specific combinations of hardware; there is no way for the developers, who do not have all possible hardware to test on, to ever find all of these bugs. Users have to help with that process. Getting widespread testing coverage is always hard; Peter Anvin argues that the current process has actually made that harder:

One thing is that we keep fragmenting the tester base by adding new confidence levels: we now have -mm, -next, mainline -git, mainline -rc, mainline release, stable, distro testing, and distro release (and some distros even have aggressive versus conservative tracks.) Furthermore, thanks to craniorectal immersion on the part of graphics vendors, a lot of users have to run proprietary drivers on their "main work" systems, which means they can't even test newer releases even if they would dare.