The credits needed to get the most expensive cars, will come to you sooner or later by just playing the game

. There is no need to increase the payouts across the board, because the payouts are very good in the game.
Players that want better credit payouts because they want to get things in the game by spending a lot less time playing which is wrong. There is no need to get everything you want in a very short time. Cars and stuff are going to be still around by playing the game for many and many months, so if you want something like some of the expensive cars in the game, well you just have to spend more time playing and put in the effort by earning credits if you want that car.
If you don't spend a lot of time playing because of real life commitments, well you are going to take a long time to get what you want in the game. The players that spend a lot of time playing by winning credits, will get things a lot sooner in the game.
There are no problems with the credit payouts in GT Sport, just enjoy the game 👍.