As far as the class stacking issues, it just takes time to sort itself out. Right now the game has 3 types of people playing, first time MMO'ers, people who quit XI because they hated dirty windower and XI elitism, and people who got tired of abyssea/old game (again XI). No one is playing this because it was such a great and innovative MMO with an amazing launch and this we all know.
When you look at what that means in terms of overall skill, we know it to be low. When you look at this in terms of general knowledge, we also know that to be low. It's only a given that people will take longer to come around to different strategies in PUG runs, and it's a given that people will want strangers to play the safest jobs for PUGs. A Ranged DD doesn't need to know how to read a chat log to combo on a moving or ambiguous target, a ranged DD doesn't have as much chance of running cracks straight into the tank/whm/otherDDs. We all know the examples. BLM is also the most forgiving job gear wise and you can pump out decent enough damage to contribute to a run while naked.
The jobs are close enough now that each one can outperform the other given player skill and the event, this is important because it's pretty rare in MMO's.