To be fair, a good chunk of the in-game credit economy will expand favourably once the game's out in players' hands. It relies on sheer numbers, so a tiny amount of reviewers playing won't help as much. Features like Rivals positively toss money in players hands, and from what I've read, Drivatar will gain folks money too, even when they're offline, as will the usual tunes and paintjobs.
I've never felt the need to buy tokens in FM4/FH because the game tossed so much money at me; GT6 certainly has the capability to do the same, and I hope it does. I don't expect to be able to afford every car within the first month, but I do remember that prior to seasonals in GT5, the grind was absolutely necessary if you wanted anything. Ideally, PD has improved the in-game economy over GT5 (which should be pretty straight-forward, what without the skewing an auction house or marketplace provides), yet the tokens still exist for those who want everything unlocked from the get-go.