They should put actual MMO players on the development team.

[Mijin]

wait, wait, wait. Your boss comes up to you and says trout lures will only be painted red from now on because "the red ones sell better" most likely because he actually has data and sales records to back this up. but because you say blues ones work better basing it purely off the anecdotal evidence of you own fishing trips, your boss will for some asinine reason ignore sales records and trending data, change company policy, and some how the buying habits of consumers will change? That makes literally no sense what so ever.

you really don't think your analogies through at all. Your "experiance" as a fisher in that analogy is of little to no use to your boss. Regardless of the success you have had with blue ones, if the public at large is of the opinion that red ones are better (hence the reason your boss wants to make only red ones) then it is in your boss's and your own best interest to make red ones.

While you're obviously over analyzing that for the sake of argument, I'll play along:

You work as a marketing consultant for a large fishing tackle manufacture. You love your job because your favorite hobby happens to be fishing. You're boss comes up to you one day and says, "Well, we've decided to sell a new lure for trout, I was thinking about painting it red because red bass lures have the highest sales." You explain to you're boss that while red bass lures are favored among fishermen for bass, experienced fishermen actually prefer to use blue lures for trout. You can attest to this because you're an experienced fisher yourself, otherwise you wouldn't have known. Your boss says, "Okay let me check with the marketing people and I'll get back to you." The next day your boss comes up to you and agrees to go with the blue trout lures, because he obviously has no knowledge of fishing, he just knows how to make lures. The blue trout lures turn out to sell much better, and everyone lives happily ever after.

Hopefully that one isn't as confusing for you, I tried not to leave any details to the imagination. Just in case:
Bass Lure = Single player games
Trout Lure = MMORPGs
Red/blue = content
The experienced marketing consultant = who needs to be added to the picture

I hope this helps you understand my metaphor (which is more like a short story now).

Knowing what customers want is just as important if a more important than sales data when it comes to making profit.