Look at it this way, the graphics engine would have to tick over twice as fast to hit 60fps from 30 which means they have to optimize it by 50%. A very big task.
Speaking from personal experience, just because it is locked at 30fps doesn't necessarily mean they would have 30fps of optimizations to find. It may be capable of running at 60fps mostly, with certain situations dipping it to 50fps or 40fps. As it has to be 30fps or 60fps, you'd obviously have to go with 30fps as a lower constant frame rate is less noticeable than frame rate drops. The big question is whether Sony can find the optimizations they seem to require.
Yeah, I am not buying that entire PC thing at all. If that is true then why are so many PS4 games at 30 Frames per second. Killzone should be running 60 easily. Nope not buying that.
I did post a likely explanation earlier. As I understand it, from a developer standpoint both the Xbox 360 and Xbox One are quite similar. DirectX is used for graphics, etc. The Xbox has a mature and very well developed system of developer tools. So all developers have got to is take advantage of the newly available power. With the PS4, Sony have gone from the weird and wonderful architecture of the PS3 to x86. They don't have access to age-old tools like DirectX (for obvious reasons), so have had to write their own equivalents. Developers have got to learn these and have probably had to significantly rewrite (or write from scratch) their own engines and tools as well. No idea of the actual FPS involved, but I can see this kind of situation evidenced in the early PS3 games I've played - many seem to have frame rate issues that their later equivalents do not (GTA IV > RDR, Oblivion > Skyrim).
No offense intended, but I think you are adding two and two and getting five. You've taken one part of an already unspecific quote from Turn 10, taken the respective frame rate differences and decided that the cloud is the reason for this, while simultaneously disregarding a whole load of far more likely scenarios. Architectural difficulties on the PS4 seem far more likely to me than the cloud being solely responsible for 60fps on the Xbox One. Given the supposed power advantage, I'd be far more surprised if the PS4 was physically incapable of 60fps (especially as none of the games shown for either console were that much of a jump visually). I'll be happy to be proved wrong when the Xbox One is released and we can see just how it all works.
We'll have to agree to disagree for now though and see how it ends up. I'm most interested in what the cloud can bring to gameplay (Ubisoft's line-up in particular is very impressive - was far and away the best presentation at E3 for me).