I think they're smart not to make radical changes to the user interface. No programmer wants the regular users to feel lost all of a sudden. However, it could use some polishing here and there.
What I would have done:
Give the A-Spec events more personality:
Allow the use of "real" settings and in turn players would receive more money and experience for competing in these events. Players who prefer the game as it used to be could keep playing on "standard" settings with the current rewards. It just seems odd for the real driving simulator to ignore damage, penalties, tyre wear, fuel consumption, competitive AI, weak slimpstream etc., when these features have been integrated. It's just wrong that you have to be in an online lobby or Arcade Mode for the ability to explore all the realism combined at once. Furthermore, entry restrictions for the events should be overhauled for both A-Spec and B-Spec. It makes little sense that we have to use a Nascar in the Nascar event when the Super GT event only restricts the car choice to a Japanese car. A-Spec events should also make use of tyre restrictions just like B-Spec. Consistency issues which make me think of something else...
Standard to Premium:
The aim for any game developer should be quality and consistency. PD adds inconsistency by giving the last-gen standard cars another dimension by adding an interior which by the ignorant player could be mistaken as a graphical bug. Instead of adding new premium cars, focus should be on turning existing standard cars into premium, so the game can catch up with the expectations people have in 2011.
Other than that I'm quite pleased with Spec 2.0 but in reality it's nothing more than another patch. I don't see what creates the huge gap from 1.13 to 2.0. Maybe if the DLC was added free of charge instead of being sold as DLC.