Well I was thinking beating a boss just isn't as satisfying as it should be. I like getting more loot and tokens are all great and dandy but really besides tokens bosses would be worthless to do. I think the spinner/slotmachine at the end should be special boss/gold edition and should drop 2x more crowns and even tokens of all variety!
It would be nice and really fill that empty space where i wished there was more loot to be had.
Anyway I kept it short and simple! I think this would make boss levels more unique and memorable for players.
The tokens are worth more than you think if you sell their stuff.
Also all the levels previous to the boss itself already give more crowns in comparison to normal levels, so it kind of balances out.