Exchanging coins for credits is a terrible idea.
I would not call it a terrible idea, it has some value ... but it will never happen without major changes to the game which are also unlikely. But i agree people would have issue from various perspectives with this but those already exist but there is less incentive to accummulate coins.
The problem as i see it, coin rooms can be used as virtual printing presses of coins which allow players to create more coins than WGT removes with their cut taken in each game and in turn creating more coins without buying them. I know of nothing in desktop credit gold that allows players to win more than what is removed in a challenge match. Yet, this is also a result from the addition of sponsor apparel.
It would likely require removing sponsor apparel and the coin game specialist would have a fit over that. I have never felt sponsor apparel was good for the game but use it for coin games because it allows me to play a much cheaper ball than i would play on desktop pc, which is also equivalent to the free ball wgt hands out. So for some players wgt is losing out on higher end ball sales due to implementing sponsor apparel. But they dont expect all players to be so practical.
So while i cant buy balls using silver coins, i save thousands of credits by using sponsor apparel with a lower end ball. I guess in that way... wgt is saving me credits.