"With buy it now two people could agree a sale before the player being listed, and closing off the option to everyone else."
No they can't as buy it now appears oly in the last 12 hours so everyone has at least 60 hours to overbid the buy it now price. If nobody wishes to give that amount then it's no harm setting up the price cause nobody would pay that much anyway.
The same can happen now. Case one: we can agree that I'll buy a center from you at the price of 2M even if he's worth only 500k. If we agrre on this no difference between setting buy it now price or just put the bid the usual way.
The opposite situation: you have a center who's worth 2M and you want to sell me for 500k. He will be on the market for 60 hours before I could buy him for 500k and if the bid goes higher the option won't be available.
Don't feed the troll