I don't think its impossible for PD to listen here, and there is evidence to suggestion that they do (Spa, Golf R for me, Lamborghini Aventador, possibly a few others), but I just wish there was evidence of it, say, an official representative that would do official polls, here, on GTP maybe 'would you prefer the new BMW M5 or the Ferrari FF' or things of that nature, then depending on what the users thought, they would select A or B and logically speaking, they would actually sell more DLC as well (if GTP is an accuracte representation of the population of users who play GT5 and buy DLC).
The OPs post has a point, its blantently clear that this is 'the' forum for all things Gran Turismo, and especially GT5, so if they were going to get it from anywhere externally, it should (would) be here, but there isn't enough evidence imo.