Because I believe in two years the inertia of so many versions of Android being introduced every couple of months will produce market share. With market share comes better apps and features.
First, the hardware manufacturers have to come up with a viable device. One year on, and so far the closest competitors to the iPad have been pretty much non-starters; the rest are still vapourware. (And Apple already has the velocity of having put two versions of its tablet on the market.) I honestly have no idea how all the other vendors are going to catch up with Apple on that one.
Having many choices doesn't necessarily correlate to larger market share, either. (Conversely, Apple captured most of the tablet market with just one flagship product, now in its second generation.) One of Apple's strategic advantages is that its product is tightly vertically integrated, and with that kind of head start... well, I don't think even their competition knows what to do next.