Rogues have, of course, been stealthy for a long time, and when word first dropped that hunters might be getting Camouflage in Wrath of the Lich King, we were pretty excited that some element of stealth might be added to our class too. Blizzard went back and forth on this ability, first putting it in, then taking it out, then putting it in again, and finally taking it out again. In the end they decided that it was just too similar to the rogue ability, and they didn't want to blend the classes together too much. This was about the same time that they gave rogues a new ability, called Tricks of the Trade, which looks a lot like the hunter's ability, Misdirection.
To one player who asked what was up with this unfairness, Ghostcrawler spoke up and explained some of their design philosophy. She started by saying that they have 10 classes now, and they have to add more in every expansion. The "lazy-designer" way to handle this kind of situation is just to find an ability that works for one class and just give it to another. This would end up leaving the classes without enough to distinguish them all individually, and it's something they wanted to avoid.
So why was Misdirection an okay ability to share, while Stealth was not?...
Was it because Stealth is already shared by druids? Or because it is such a core element of the rogue and druid experience, something they get from very early in their carreers, while Misdirection was just added on in the latest expansion? Was it because the purposes to which these two abilities would be used by these two classes was different enough that it wouldn't make them to similar? Or was it because of actual threat-per-second calculations laid out on spreadsheets and carefully analyzed by the development team? No. In the end, Ghostcrawler says, "deciding what kind of abilities they have is more of a gut thing, and logic isn't necessarily going to apply the same way." The design of your class is a gut thing -- like music, and painting.
It got me thinking. So who's the judge? Does Blizzard get away with all their unfair class design choices just because their gut says something our guts don't say?
The answer, my friends, is yes. So much of what we see in the game is that way because the developers just felt like it was the best way things could be. They didn't get it right all the time, as Ghostcrawler will readily admit, but overall it looks like they didn't do too bad, considering, you know... 10 million players and counting. It strikes some kind of chord in people as a meaningful activity. We may not agree with their class design choices from our own rational perspectives, but WoW really is a work of art whose value mainly rests in what it means to each individual. Logic isn't the only (or even the most important) factor in cases like this, and the balance of abilities they're trying to reach is essentially aesthetic.