I see a few problems with this plan
1. Platinum will become the new Gold.
The talk around the forum is now whether or not you have gold. As soon as PD introduces platinum, the whole gold thing becomes irrelevant and gets replaced by whether or not you have platinumed
By making the gold times easier, PD reduced the number of frustrated people. By adding platinum, they will increase that number again. People won't be happy with gold, just as they are not happy with silver now.
PD makes many gaming decisions that are not aimed at the casual gamer (if you compare to a true 'game' like S2U for example). I think their choice to adjust the gold rewards to more casual gamers is a good one.
2.Within a day and probably within an hour the time needed for platinum will be on GTP. Making the times 'secret' is kind of useless as everyone will want to know what they're aiming for and the internet will provide this information, as always.
3. One player's 'easy' is another player's 'hard'.
This is kind of the same to @
huskeR32 's point above, but in reverse
There are many people who have trouble golding these time trials. About half of them have been a challenge for me as well and I wasn't able to gold all of them in stock cars.
Besides that, going by forum posts is not a good method to find the difficulty of a race. The more people who shout that something is 'easy' the less people will come forward and admit they had trouble (even though I am pretty sure most if the 'easy' comments are a bit exaggerated).
Only online times can tell how easy it is to gold the races, as you can count the number of players (accounts) who have done so and count the number of players who haven't. And even that doesn't tell you how much effort was needed to gold the race. In other words: While it might be easier than in GT5 (I agree with that) it might still not be easy for the majority of players.
4. As mentioned before there is a leader board for the people who like a challenge. If getting higher up the boards is not a reward in itself, you can question the dedication of the 'hardcore' gamers.
Yet now you question the dedication of the casual gamers.
Which brings me to
5: Many people on this forum seem to want to dictate how others play their games. Why do 'casual players' need to try harder and (referring to 3) how do you know if they aren't already trying?
I sure know I have to try hard (or tune my car, which I don't prefer) to get gold.
it is not like GT is training people to become doctors and one of them might have to save your life one day. It is a bloody racing game.
Having said that, I do think there are things PD could do to reward people for trying for better times, but things that wouldn't mess that much with the ego's of both the 'hardcore' players and 'casual' players:
They could bring back the PP difference bonus or they could give credit bonuses for every .001/s you are under the gold limit. This way you would have a bit more of an incentive (if the leader board is not enough) and it wouldn't mess with the casual players.
They could (and should in my opinion) keep different leader boards for SRF on and SRF off or some way to filter the results. SRF is just too much of a magic thing to include in leader boards.