Perhaps this is done with new users in mind, and not veteran eggheads such as yourself. There will always be new riders in the game who need training wheels. If a newbie makes bids on 7 doctors, and somehow (not that this would happen but theoretically it could) manages to win them all, he could stand to lose quite a bit of money in a short period of time without really knowing.
I think your suggestion is a good one for myself, but I can see it being problematic for new users who don't really undertsand what they are doing yet and might get into some financial problems by hiring and firing seven doctors in one day. That said, maybe there could be a BB probationary period where full funcionality of the game is limited for a month of something- sort of the like the different levels on the tactics page.
Once I scored a basket that still makes me laugh.