Except here, part of the griefs are easy to fix, as the base material is present and it is only a matter of setup and deliberate choices.
Like delivering a more complete solo campaign, having more events for all tracks and cars (some categories have few or zero events).
Like being coherent and just on the credit rewards (not slipping some high gaining events here and there so the players can grind their way to obtain enough credits). Credits should be coherent with the length and difficulty of the event. Sport Mode should be much more rewarding as it is harder to win against fellow humans than the lame AI.
Like offering something else than the "rolling start dead last, pass through the slow AI to reach fast AI before the end of the race"
Like offering the ability to qualify before a race (to fight with better AI during said race).
Like fixing the wheel of despair.
Like removing the expiration date of invites (or getting rid of them)
Like being "realistic" not only to set the price to buy cars but also to sell them (why the Ford Mark IV is priced 6.4M but if I buy it and later sell it, I'll get 3M if I am lucky?)
Like giving the possibility to redo mission events and regain the reward.
And the list goes on and on.
Nothing complex, nor time consuming, nor requiring new development, just some setup and better decisions in favor of the players who want to enjoy the game which has tremendous qualities otherwise.