Not really into doing these kind of things either, never done them before, but after completing the races on offer I like to then try them with other cars hoping for close, challenging races but as the rewards for winning, or as you say the roulette wheel rewards are so shite, it either means grinding for days on end earning 50,000 credits a time or instead grinding for an hour or two and earning 10 times that amount which thereby opens up the game to be enjoyed using other cars you can buy.
I don't mind doing the same race a few times if that then allows me to do it again using other cars and keeping the game enjpoyable, but I can't be arsed doing the same 50,000 reward race a hundred times just so I can afford one legend car costing five million. How many races would it take to get half of the cars on the game in that case?
Agree with what others have wrote on here that it's not so much a racing game, more a time trial with obstacles but it is a great little game. As I said earlier, it needs more races and obviously this started with yesterday's update.