Then the N900 isn't what you should be discussing. The mobile data market outside of handset data is just now emerging, so a solution an ubiquitous does not and will not exist in the lifetime of the N900. Because of this, WIMAX on the device is mostly just going to be a waste of time and money.
Scope and timeframe are important issues. Yes, ubiquitous mobile data is a good idea, and, yes, I'd like to see it implemented in future ITs—but not before the market gets to a point where it isn't going to be more than a fancy decoration (especially for those of us with data plans).