That looks to me as if GT4 has more than just the one thing making it different to GT3...
Of course GT2 wasn't just GT with better graphics and more cars? And wasn't that highly disappointing? And look how few copies it sold too. But more importantly look at how PD tried to do too much and rush the game out for baying public hounds only to release a bug-ridden hash.
I guess extracting more graphical performance from the PS2 than anyone thought possible, 50 discreet tracks and nearly 800 cars - all displayed using this unparalleled graphical performance from the PS2 - just isn't enough for some people, eh?
How many people complaining about the lack of "true" online racing in this thread have actually bothered to drive every single car in GT3? How many of you have driven all of the Arcade cars - the ultimate levellers - and participated in online databases, such as those at GT3Times, Racing-Line and the Arcade Car Database at GT Racing Point, databases which are policed for cheats by eminantly qualified racers and replay verifiers to determine the very limits of human capability in the game? How many?
If you don't participate in these databases - which is basically the GT3/GTC/GT4P equivalent of what you'd call "true" online racing - what makes you think that any one of us who do would want to race online against you? How can you know how good you are unless you are racing against the glitterati of GT3 - Arco/Wiese, jmr, Max. E, Mr. P, Slowpoke and the like? What makes you think that online racing against a bunch of numpties whose idea of car control is smashing into you on the inside to turn a corner? Online racing for you will be a hollow experience - filled with hollow victories and hollow losses because you don't want to participate now, so the people who are actually any use don't want to participate against you in the future.
Now shut up your inane, brain-dead whining and be thankful for the game that is about to come out. And remember, the first Gran Turismo only came about as Kazunori Yamauchi wanted a decent racing game for himself. You don't have to buy it, but if you own a PS2 I suggest you probably should.