because subsidized phones generally are crippled and come loaded with the provider's crapware, for one thing. While the N900 might be different, generally you can't compare the unlocked version vs the subsidized locked version in an apples-to-apples way (E71 vs E71x, for instance).

And it takes just one international trip to realize the advantages of an unlocked, non-crippled phone that can use local SIMs and VoIP applications That may not be beneficial to most, but it's saved me thousands in roaming fees over the years.