The problem with beefy DLCs is it either pushes back the effective release date of the game, or annoys the customers. I like to get involved in the game I'm playing. I don't switch games at a drop of a hat - I play one game through to completion (or give up on it if it isn't good) before moving onto the next and I don't like to be forced to go back to it. That's why if a game is 'episodic' I don't consider it released until the entire season is out.
Although I really enjoyed playing the White March and White March 2, I was very upset that I had to find a save game before the end to play through with. Had I known it would have been like this at the start I would have just waited the year or so before it came out before starting the base game. I just found out about the DLC to Tyranny today. I loved that game, it fixed all the mechanical problems I felt that PoE had and had a great story and characters (Lantry and Kills-in-Shadow in particular, although the third act was very poorly handled). I wish I had access to the DLC back when I was playing the game though - as much as I loved it reinstalling it and starting again is a time commitment I just can't make.
So please, if you have to make DLC to pay the bills, please focus on stand-alone expansions set after the main campaign a la Mask of the Betrayer. They're easier to come back to, and (as pointed out in the OP) they're cleaner from a narrative perspective.
