This reminds me of a discussion a friend and I had several years ago. I posed the question to him, "if you had the choice of winning 20 tournaments in your career vs. only 1 major and nothing else, which would you choose?"
Without hesitation he said "the 1 major". I didn't agree with him at the time, and I still don't agree with him now. If you only win 1 major and nothing else to back it up, you're going to be pretty much forgotten. While the majors are obviously more important, and for good reason, I think you need some other wins to validate yourself as a solid player.
20 years from now, if nothing changes, I think history will be kinder to someone like Colin Montgomerie than to Shaun Micheel.