From what I remember, it was quite the opposite.
Sony wanted PD to create a new GT game as cluster-platform where players would buy content depending on their personal taste.
Kaz/PD/whatever went against that idea.
In few interviews Kaz discussed whole DLC "philosophy" and he clearly stated that his idea is that every player can enjoy in the same level of content during lifespan of the game.
Later he even went against whole concept of DLC-content by proclaiming that whole content of GT5 will come on the disc, without any DLC. Of course, whole mess-up with the deadlines, finishing the game and actual release of the Gold went differently, but I presume the pressure for both SCEE and SCEA was too big at PD. That is wahy we're getting basically weekly content-updates (in terms od Seasonal Events) and functional updates (1.01, 1.03 and 1.05 being most important) for free.
It is really difficult to say what will future bring regarding GT5 "actual" DLC content (new cars and tracks) but I think that if Kaz is the one who will be asked - he will probably decide to go "free" way.
Also notice that Japanese people are much more influenced by whole concept of "honor" than any Western people. He apologized even before games's release for technical problems, he later even admitted he knows that some design choices went bed and I think he's very aware about shortcomings of the finished product. And just to throw, in his initial "dream", Gran Turismo 5 was meant to be "The GT of Them All". I presume he is actually the one most dissatisfied with the final outcome of the project. I know it is fishing in deep waters, but I wouldn't so easily thrown-out the factor of "honor" from whole DLC context.
Time will tell, ultimately.