Originally Posted by
Sadinar
I want to reiterate this point, because I think this is by far the most important reasoning behind these dungeons. When designing dungeons, Blizzard has 2 options. They can A. Make dungeons slowly increase in difficulty resulting in players learning their skills as they level in dungeons, or B. Make dungeons easy throughout the leveling process. While it SEEMS obvious that blizzard should choose A, there is a significant problem to that. No one will do dungeons if questing is faster. Now I don't obviously mean no one, but the fact of the matter is that blizzard has to choose one of 2 evils: they can either make dungeons not prepare you for content in the end game, or they can make dungeons a much less popular venue to level with.
Blizzard has clearly chosen the latter. While its easy to say now "Why don't they make it like option A!", the thing to realize is that if they did do it like option A, then we would now have people coming in saying "man there are so many scrubs in leveling dungeons, we can't even get maraudon down people can't avoid the princess' attacks!", much like we see all the time in threads for heroics. And blizzard seems to believe that such a thing is worse than not having people prepared for heroics.
Whether I agree or not, its important to realize that its not as clear cut as "make dungeons harder!". There is a significant cost to it, one that the developers have deemed not worth the benefits.