In some cases, that is a marketing thing.. They sell you something almost perfect, and the only thing that it misses to be perfect will be shipped in another phone from the same company. For example, N900 and flash 10.1, it wil be on MeeGo only. On the Xperia X10 it is a marketing thing too, because they want you to buy the new Xperia Arc that has THE SAME STUPID HARDWARE but the Android version is 2.3. Recently, I saw an article where Sony said that they think that the Xperia X10 is perfect the way it is, so they do not consider that the update to froyo or gingerbread where necessary. But the real truth here is that they want you to buy the Xperia Arc with the same specs.

In other cases, the imperfection of the devices is fault of imperfect companys that think they are perfect, like apple.