I do think the current end game leaves much to be desired, but I don't really agree with the OP.

What end game right now is lacking is variety, and that's pretty much it. The fact that you can not use DF for certain things doesn't really negate it as an end game option.

The current problem with end game is lack of content available to gear up for coil, and poor/lazy itemization. Getting your Ilvl 70 suit should not consist of 1000 boring, trivial CM runs. Getting your Ilvl 90 suit should not consist of 100 AK runs over a period of 20 weeks. There should be 8 man challenging content that get this gear, and there should be some gear options for that ilvl bracket.

The game is still young, and I am sure End Game will receive much in the way of variety. But in its current form all end game really is is your relic quest, coil, and running 2 trivial dungeons over and over and over.