Cash shops are an easy way for game developers to make money on a free to play game but who are they hurting in return?
Free to play games usually have high level armor, weapons, and extra gadgets players can buy at cash shops. This is a potential problem. The people who are playing for free think they have a fair shot in the game untill they get ganked in the wilderness by someone who just baught a new pair of armor with real money. This is never fun, well for the player getting owned atleast. I personally baught something from a cash shop once im not gonna lie. I did feel like i had something a lot of people didn't but i kind of felt demoralized. So the fun can be sucked out of the game even for the person buying the items.
Equal oppurtunity grants players with a sense of justification. If they know they played a fair game then the game will mean more to them. Chess is a very good example of this.
Im not saying drop the cash shop gig. There are rational ways of giving players extra content without ruining the game for other players. Instead of offering stronger armor and weapons, offer a variety of armor and weapons with differnt classifications. Not nescisarily stronger but differnt and unique.
Don't sacrifice good gameplay for a quick buck.