Stupidity.
From a good source at Sony I have it that AT&T were willing to take the Z3 at near launch (early November) with T-Mobile (beginning October) and VZW (end October), but they wanted a special colour and to offer the option of 16GB and 32GB for $199/$249 with a two year deal. They were close to signing a deal when Japanese level management stepped in and said they felt it would be confusing for consumers (ignoring that Apple and Samsung do it quite successfully) and that they couldn't run a different production lines for 16GB/32GB variants of Black, White and the special colour that AT&T requested (metallic gold back with a white front iirc) without reducing the margin so the counter offer was 32GB and black, the same as what T-Mobile is getting with Copper at a later date with 32GB. AT&T declined.
If I was a senior manager at Sony I would basically be doing whatever it takes to get on three of the four major networks and then get the fourth as quickly as possible after that, then roll out lower priced devices on those networks afterwards once my central offering is proved successful and the brand was built out. I would also be pushing devices like the E3 and T3 on Boost mobile and local carriers as pre-paid with $149 and $249 prices, again to get the brand name out there among the local population who don't realise that Sony make smartphones. Finally I would have priced the Z3 Tablet Compact to sell at $269 and had a massive advertising campaign for it and the Z3 with celebrity endorsements and huge TV presence with adverts that make it very obvious what the phones are good at (battery, battery, battery) leveraging brands like Walkman, Cyber-shot and PlayStation which are already familiar to US comsumers.
If an outsider like me without all of the information can see it then I do wonder what goes on at SMC, the management is just absolutely fucking awful from what I have heard about them.
Artistic conflict with Avi Arad who is very big at SPE. If Sony had dumped Arad like Marvel wanted they would own it.