Very true. Most of the new high level content is kind of "bleh" and there is no end game in DDO currently.
But most of the earlier, lower level adventures are a blast of fun. Also there is some hope, as the newest update had a high level quest "Study in Sable" that is definitely a classic D&D adventure.
The character customization options in terms of the different builds are amazing. (13 classes, where you can mix and match up to 3 of them, 8+4 races with racial abilities, 21 skills, 2-4 enchantment trees/class+1/race, dozens and dozens of feats to chose from..)
To add to the fun they have a Reincarnation system where you can after running through the fun parts of the game (reaching level 20), you can "Recycle" your character and start again at level 1, with (slightly) more power. And for those of us who are addicted, that process can be repeated again and again, each time gaining bit more power.