This is a horrible move for SE, anyone in an active ls right will not be doing those dungeons with a bunch of 30s. SE essentially wasted all their time developing this 30 dungeon if there is not going to be a level restriction to it.
The lower level dungeons need to be level capped just like CoP, anyone can do them but their level us reduced to the maximum level that could enter while they are in the dungeon.
If there is not a barrier to entree, there will be no sense of reward in that dungeons... it will just be another meaningless time sink because there will hardly be any groups of 30s in it it will a 50 zerg fest which will get everyone the gear fast then everyone will stop doing it. No accomplishment, no feeling of reward = no fun.