What? I never said anything about that not liking that the Warden is in Awakening. I'm saying if the Keep forces him to be, then it's fine. But it should also force Hawke to meet Tallis. There is no reason for all DLC to be mandatory except Mark of the Assassin.
But, again, DLC isn't mandatory... Sebastian's and Shale's(everything after you could have recruited them) both aren't...
Hawke and the Warden's participation in each is only mandatory if there is no way for the events to have happened without Hawke or the Warden. Awakening doesn't happen without the Warden unless he's dead. Because he's the Warden Commander of Ferelden, again, unless he's dead. Same with Golems and Witch Hunt. Hawke must participate in Legacy because he's the Key, and Hawke's siblings might both be dead.
But Tallis doesn't need Hawke's invitation to get to Chateau Haine. And she doesn't need Hawke's help to get it when she gets there.... That's why Mark of the Assassin is considered optional.