While your explanation makes a lot of sense, the jaded part of me finds it difficult to believe that a publisher the size of Sony, especially given that they aren't particularly player-friendly, would stop a developer from overmonetizing a game. I don't believe for a second there's an ounce of good will in the upper echelons of AAA gamedev. No money is ever enough for them.
Still, publishers can have a degree of power over what's included in the game, which would explain why GT7's Roulette makes no sense without monetization. Nothing aside from a publisher's no-no was stopping Polyphony from monetizing the hell out of Roulette like they obviously intended to.