I think the underlying problem is the lack of incentives for people to perform code review.
It's very time-consuming and difficult to do properly; displaces time and energy that people want to use to create new code (because there are incentives for that); and there's not much in the way of recognition.
There must be some way to recognize the efforts of reviewers. Perhaps we need a "Bug-found-by:" tag, and for stats on that to be used as part of the various reports on who is contributing to the kernel. It might also be worthwhile to have some kind of live scoreboard at kernel.org or lwn.net.