I would have waited, in the sense that I wouldn't have bought GT5 before it came out but I would have bought it when it did, if you get what I mean. I think PD came dangerously close to Duke Nukem Forever-style endless development resulting in a sub-par, dated game. As much as I hate Call of Duty-style yearly release games (one year of development time is not enough, and that really shows; Call of Duty has made about one year of actual progression in the time between MW1 and Black Ops, and MW3 doesn't look that advanced compared to MW2), there is a middle ground between not enough time and too much time.
Too much time is not good, everyone thinks 'oh, but the things we could achieve if we had time!', but the fact of the matter is, having all the time in the world is a very, very bad thing. For example, I'm a graphic design graduate. Just after I left Uni, I decided I was going to take some time to work on projects and do some freelance work while living at home. I started off well, working hard, but I started to try to do far, far more than was feasible and never actually finished any projects. Deadlines are important, they keep you focused on what's important so you can filter out the unnecessary stuff.
Kazunori's vision is one of huge ambition, and that's great, but GT5 should have been GT6 and GT5 should have come out in 2007/8. No, it wouldn't have been as good as GT5 is now, but it would have been an improvement on GT4. I think the point I'm trying to make is it's all well and good having a vision for the future, but it's very, very bad to try and get there all in one step, especially if it's gaming we're talking about.
TL, DR: PD need to be happy releasing games that don't live up to Kazunori's vision, as long as they are an incremental improvement and eventually lead to a game that does live up to that vision. I really, really hope the unfortunate circumstances behind GT5's release has made Kazunori and all other developers realise that too much time is not good, it's just as bad as not enough time in many ways.
Finally, I don't get why so many people actually want DLC from day/week/month 1, that's ludicrous. GT5's DLC could have come a little bit sooner, sure, but to suggest it should have been out before the end of 2010 baffles me. In any other game, early DLC is just a poke in the eye, saying 'we could have given you this when you paid £40 for the game, but frankly we didn't have to so we'd rather charge you extra for it'. It's greed, nothing more, nothing less, and we as consumers should be 100% against it because if we're not, in three years' time we'll be paying £40 for 50% of what we used to get in the PS2 era, and the other 50% will be overpriced DLC...