I believe if this was a different type of business it would have no returning base customer.
The lack of professionalism is personal opinion, depending on what you are expecting as a customer. If a member of my staff ever spoke to a customer in this way. I would have to say that they would no longer have their job.
But as this is online gaming and has very little rules they are able to get away with more than anyone when it comes to customers.
The only way this would ever change is if the customer took it upon their selves to seek a better service. I.e stop coining or playing. As with every game it's the addiction factor that keeps people returning and playing.

Just my 2 cents.