Should Blizzard buff/nerf classes based on popularity?

This question has been on my mind ever since I read a WoW.com post that said that because druid tanks were the least popular kind of tank, Blizzard was hesitant to nerf them. This was part of a longer article about the relative popularity of certain tank classes, which showed that warriors were the most popular tanks by far, with druids being the least popular. The article speculated that the reason for this was that warriors have always been viable as tanks, but paladins and druids only became popular as tanks with the advent of Burning Crusade. Even then, paladins were arguably better tanks than druids, and only recently have druids become truly viable as tanks. Death Knights have been popular ever since they were added to the game, which explains why they had no problem carving out a part of the tanking community for themselves.

But I digress. The fact that Blizzard was hesitant to make any changes to an unpopular class got me thinking: should Blizzard buff or nerf classes based on how popular they are? Although the popularity of a class can be viewed as an indicator of its relative strength compared to other classes, such a comparison is misleading. After all, for the longest time, hunters were the most popular class in the game due only to the fact that they were a good class for newbies. Death knights are now by far the most popular class, but I would argue that this is due to their newness, and not their relative strength compared to other classes. The popularity of a class can be based on many things, meaning you cant take it to be an indicator of that class's relative strength.

This means that Blizzard can't use class popularity as a guide on how the classes should be buffed and nerfed, but does that mean that it shouldn't factor in at all? In an ideal world (of warcraft), it wouldn't. The classes would all be able to stand out on their own merits because they would all be fun to play, and thus you would have players dedicated to their class who would play it come hell or high water, even if their class were nerfed into the ground. Thus, if every class is fun to play, then Blizzard doesn't need to factor their popularity in how they buff/nerf them, since that class's devotees would continue to play as that class.

This begs the question, though; are the classes fun to play? Having limited experience with the various class, I can't truly say. I suppose the fact that, aside form death knights and paladins, the other classes have more or less equal representation at level 80 could be a sign that people enjoy playing all of them. Each class and each class's specs are unique in their own way, meaning there is something about each the ten classes and 30 specs in the game that appeals to some kind of player. That said, there are certainly specs that are more limited than others in terms of how they can perform their role (holy paladins, balance druids) and perhaps they could be fleshed out a little bit more, but people still play them, so they must be enjoyable in some way.