He could have phrased it better, but it's a fair point. Nintendo's core development teams have played it very safe. Newer studios like Retro and EAD Tokyo have been a bit more creative, but still stayed within established franchises. You have to go to a studio that Nintendo brought aboard just a few years ago to find a truly original title, which says something about how much of a priority that is for Nintendo.
EDIT: To get back on topic, though, and to be a bit more upbeat, yes, there have been a lot of Mario games recently, but they have been, for the most part, great. All four of the Mario platformers released in the last five years (Galaxy 1&2, NSMBWii and 3D Land) would be in my top five games in the series, alongside Mario 3. If they keep up that kind of quality I don't care how often they release them.