Is there any reason for GT6 not to be a PS4 title? I still don't understand that, it would be much better for both the game and the console. The only theory I have is that Polyphony wanted to keep the tradition of two GTs on every PS.

nothing the cloud can't fix

This is what AI is like when you don't have the power of the cloud.

EDIT: Damn you, guy above me!

Never understood the passion behind Gran Turismo and Forza. Beneath the shiny visuals lies boring and monotonous gameplay in my opinion.

So the only reasons to upgrade would be the ever so slight graphical upgrade and the subtle boost in realism. There was no reason to put this on PS3 again except to get the additional sales.

If Polyphony Digital didn't waste so much time and resources trying to get the full power or close to the full power from the PS3 with GT5, they would have actually been able to release a good looking game earlier than 2010 and get a much more noticeably better looking game with GT6 sometime in the future, The sales for both games would have been good and the PS3 would have probably sold a bit better with an exclusive that came out earlier rather than four years after the system launched.  It would have been far more profitable for Sony.

Polyphony DIgital is a great studio, but probably the worst of Sony's bigger studios when it comes to being profitable for whatever console. There's a reason why Motorstorm isn't on the PS4 as a launch title and DriveClub is, and it's not because the developers wanted to try something different. It's to have a simlike/simcade racing game on the console to compete with Forza and still push sales to car enthusiasts while Polyphony wastes time with Gran Turismo 7, like we all know they're going to do.

Better shade of blue?

I certainly like the blue hue on the Nissan in GT6 over the one in GT5.

The ability to drive a car you will never, in your life, own.

I have no eye for these things, but it looks about the same as GT5. The text description makes it sound worse. Effective AA > a few more pixels in one dimension. 16 cars > 6.

Drive Club etc can look better with less effort because they don't have to code to the absolute limit of performance or make tradeoffs.

There's no reason whatsoever it couldn't have been PS3+PS4.

I find driving boring and monotonous. My car gets me from A to B an that's all I care about. This is why I have no interest in paying for GT5/6 or any other sim racer. Love Burnout and WipeOut, though. Really hope that Drive Club is more of an arcade racer than a sim. If not, then the social features really need to pull me in.

EDIT: Certain modes can be fun, though. Off-road racing in a sim game I can enjoy. It's something that I don't get to do every day. 

It's a complete different game but you need to play it (the demo at least) to understand... pictures will be the same with better lighting/shadowns in GT6.