Yes.
Okay, long answer :-)
The pricing model is such that retail stores make almost no money on add-
on packs. Since their shelves are perpetually full they won't allow
anything to take up space that has little chance of making them money.
That's why you're seeing so many "new" games that are minor rehashes of
existing games. As recently as a few years ago, Ubi Soft probably would
have released MGPRS2 as an add-on. Giving them the benefit of the doubt,
they were apparently caught off guard by how quickly add-ons were
squeezed off the shelves. With better planning, they could have released
a sim in a different area of racing (CART, Touring car, GPL competitor,
etc.)
The game companies can't afford to rewrite their engine for every game.
And gamers aren't willing to wait 18-24 months between releases. So game
companies have to plan for at least two games from a given engine.
Mighty