The old maxim, “The customer is always right” has been applied to game design design discussions a few times. Basically the arguement goes that since players want unit X or upgrade Y that they should get it.
The problem being that often this isn’t a choice between players not being able to access a unit but the unit or upgrade in question being official or not. So the question then becomes, should players always get access to popular units or upgrades in official army lists?
I don’t think so. One of the aspects of Epic that has been ongoing since the initial playtest versions of the game is the “counts as” rule and the Collectors Models appendixes. Players are often given a wider number of units and weapons to use in friendly games than they are in tournament army lists. Often because the old units or weapons won’t be published, the models are rare (or from Foregeworld) or are not balanced or easy to balance.
Building a balanced army list for tournament play is difficult. And some times this requires designers to remove options even if they are popular. But, I think, as long as those options are still available for gamers to use in friendly games that the issue of the “customer” being always right isn’t an issue since the units or upgrades are available to players, just not as GT playable units.