Years ago, receiving email on your smartphone was a benefit reserved only for highly paid executives, now anyone with an Internet-powered smartphone can do it. No longer is that a niche that RIM can rely on to power its business into the future. They, as any other business who wants to evolve, has no choice but to grow with the needs of their consumers, and RIM recognizes the fact that they can't compete with Apple in the app market simply by throwing more developers at the problem. What they've decided to do is focus on the quality of their apps and not simply the quantity of them.
Quality over quantity seems to be the path to success for RIM and their app development portfolio.