I know I sound like a miserable old sod but I think GT5 is the best driving game/simulator of the lot.
And? Of what value is this statement? Someone can post that they think turd sandwiches taste fantastic, but 99.9% of the population will still strongly disagree. The thing about personal opinions is that they aren't worth anything.
Based on the remainder of your post, it appears that you've chosen to focus on the parts you like and ignore the rest, and consequently you've decided that GT5 is "the best driving game/simulator of the lot". Using this philosophy, I can sell you a house of which 80% of it has been destroyed in a fire but we can choose to focus on the 20% that is still fine and label the house as being "the best house on the market" because the undamaged part of the house is fine.
I don't get why most of the people on here seem to spend more time slagging PD off than actually playing the game, yes there are bugs, and bits that need fine tuning, but if people just played it instead of hunting high and low for things to moan about they might enjoy it.
1) It's the Internet. Sharing/voicing concerns/complaints is a big part of that. This is a place for communicating and that's what people are doing. They do that as an alternative to just playing Gran Turismo for sixteen consecutive hours every single day. Even folks that like the game still need a break to do other things, like voice opinions on message boards. Spending a handful of minutes posting on message boards doesn't mean they're "spending more time slagging PD than actually playing the game". They can spend twenty minutes "slagging PD" and still spend hours on GT5.
2) It's not so much about "bugs" as "missing features that really should have been there to be competitive versus the competition" or "poor design choices" and stuff like that.
3) Going back to my turd sandwich illustration, if people just ate the turd sandwich instead of hunting high and low to complain about the turd sandwich, it would still just be a turd sandwich. Just playing a game doesn't make a game become better. Just playing it doesn't add features to the game or change poor aspects of it. Rather, you're simply insisting that people just turn a blind eye; just ignore the broken bits.
People don't complain because they spent too little time playing the game. They don't complain because they spent more time complaining than playing. They complain because there's things to complain about. If there are things to complain about, complaints need to be made, because if the community is vocal about what's wrong with the game then if PD happens to pull their heads from their butts they might catch wind of those community feelings and perhaps improve on their product. Refusing to complain and just pretending everything is perfect is part of the problem rather than the solution. If I start kicking you in the crotch, will it do more good for you to complain that you have a problem with it or to pretend that you're happy with me kicking you in the crotch?