If distributors are allowed to charge more than MSRP for LEs, then Stern should stop advertising MSRP on LEs. Distributors are the only ones who can buy the machines, they can just gobble up all the inventory unopposed, and charge whatever they want. That feels unfair.
That said, the whole system of LEs is a cash grab anyway, and you should know that's what you're signing up for. These days, you often need to be on a list for them before the game is even announced. Yeah, you get different art, but manufacturers could just sell unlimited Premiums in various art packages.