If everything in the game could be bought with the in-game bucks, like in real life, I could play the game however I want, and buy whatever I want in return, the game would become fun.
These games are like if in real life, a doctor went to buy something and the shop said "Sorry, we can't take your money because you earned it from working as a doctor. We only accept money here that was earned from working as a refuse collector.".
I enjoy the custom mode so I can't agree with the complaints about it
(although I can understand and sympathize), but I completely agree with everything else.
And although it's not to your point, what you said also explains why I love the main stage at Motorfest and hate the Forza playlist.
Both events have in common the fact that they are limited-time events consisting of one month-long season made up of four one-week mini-seasons.
However, in the main stage, all you need to do is collect XP, and the method you use to obtain that XP doesn't matter. So essentially we can just play the game however we want. There are also weekly challenges, but these simply make it more efficient; they're not something you have to complete.
And the Festival playlist is completely different.
You're forced to play specific races and championships with specific cars and categories, and you don't even have the ability to choose the AI or challenge difficulty. Of course, you don't have to complete every challenge, but you're still forced to complete a certain number of them. This was really painful.
No matter how tired you are or how much you want to spend your time on other things, you can't escape the challenges. I eventually gave up and quit the game, but every week for the last few months until I quit was depressing. Races I didn't want to do. Cars I didn't want to use. AI that openly cheated by rubberbanding. I was fed up with it all.
Now I can play the game however I want without feeling that stress or pressure, and it's truly enjoyable.
"I'm tired from work today, so I'll just skip racing and collect some XP from treasure hunts."
"Tomorrow is my day off, so I'll grind for some rally raid parts."
"There's a livestream I want to watch, so I'll watch it while playing drag racing with one hand."
I play the way I want, and before I know it, I've earned a major Main Stage reward.
Plus, even if I miss the Main Stage reward, I'm guaranteed the Main Stage Legacy. So even though there is an element of FOMO, Motorfest is a great game for me to play without feeling any of that pressure.