let's have a look at one of the other major flagship titles for the PS3, Uncharted.
Uncharted 1: Nov 2007
Uncharted 2: Oct 2009
Uncharted 3: Nov 2011
Well poop, I thought Uncharted was longer than that. Regardless, you can argue that Polyphony should have 200 or more staff like Guerilla Games, but PD are also involved in a completely different production environment than other game studios. Racing game developers have to deal with a million issues and expenses, not the least of which is shipping entire teams around the world to absorb tons of data on real world racing locations, including the architecture of buildings and shops inch by inch in Rome, London, Madrid and possibly more for GT6.
Let's do bring Turn 10 into this. In order to produce Forza 4, Microsoft hired a massive team from a number of contractors literally from around the globe, to the point that more than 400 people were working on it. And a Hollywood graphics studio to develop the lighting engine. This likely dwarfed the cost to produce GT5, which in 2009 had already reached an estimated $80 million, and could explain the absence of Porsche, as the price tag had already reached exorbitant levels. And SONY is nowhere near as rich as Microsoft.
We don't know how many people Polyphony has working there right now, estimates say 140, but who knows. And who knows what they need, or if they'll hire more. All I know is that they do what they do as they see fit, and Gran Turismo 6 will be released whenever, and we can complain about it all we want and it won't matter.
I gotta agree with SimonK on this one. Your reason here don't even make sense. Having time of day and weather for all tracks is a pretty big deal, and it's something to look forward to. That's like saying, "hey they have this car and this track modeled, that means we'd have it by now." Like the unavailable tracks we've seen in recent trailers, just because it's modeled or finished at this point, it doesn't mean we would have it by now and probably being saved for GT6.
The only problem would only have to be development "time" not because they can't do it due to the PS3's limitation. I mean sun angle? A huge track like Sarthe, Route X and Nurbrugring can be accomplished and smaller original tracks like Tokyo and HSR have to worry about sun angle? I could be wrong though, but until I hear a legit reason, I'm going to believe having day/night/weather can be applied to any track they want with the PS3 hardware.
Okay, my post makes no sense, but yours does??
You're sort of answering your own post in a roundabout way. It's obvious that weather and time of day can be applied to all tracks. The reason they aren't most likely isn't because they're keeping that for GT6, which would be silly, or because they're mean and can't be bothered. It has to boil down to technical, time and work requirements which having a track adjusted to suit a variable environment does require modelers and artists to open those files and rework them. Maybe this puts things in more perspective.