The reason it's not on DF is precisely because it's more difficult. Yoshi stated the DF is only for convenience for the less difficult content. The more difficult content requires skill, coordination and planning that you simply aren't going to get out of a PUG. If you think it's bad you're failing with manually made groups, it would be 10 times worse if you tried doing it with a PUG.
The biggest issue right now is simply the lack of players at the stage where they need to be doing Hydra. If you're on a new server and you're doing Hydra, you're one of maybe 10% of the server that is at that level. It's a little better if you're on a Legacy server. And even if they opened it up to the DF, the queues would still be quite long for anyone but tanks and healers.
It's better they keep the difficult content off DF until the first level expansion.
