Let us Trade Gil for Cash
Because trading Cash for Gil is effectively the same thing, it's just a different form of currency now.
You're offering players who're wealthy in the real world an in-game edge over those who aren't.
So why not give players who are wealthy in-game an IRL edge over those who aren't?
It's just exchange rates now, so why not?. Virtual or not, people care that offering an inequitable advantage in-game to players who have the $$ IRL.
What's stopping you?
You've provided a minor form of P2W by offering players a paid-advantage in game... so let us P2W Real Life.