I don't think that really matters. Imagine someone makes a disease, and starts infecting people with it. Should you really dismiss the guy who says, "hey, this disease is bad, stop infecting people with it" simply because he doesn't make a vaccine?

If anything, not making anything means you are less likely to be biased. Steve likes the iPad because he made it, not because it's intrinsically good. This biases his views on how it affects the software world.

Anyway, making something is good, but not making doesn't mean that your commentary on other people's products is not useful.