The way I see it, Chaos Space marines were WAY WAYYY overpowered and needed a leash in order to be at least remotely balanced with the other armies.
What I don't care for is the overwhelming generic'ism of the Chaos Legions and Daemons, but at least it's at least somewhat balanced in comparison to Space Marines.
In this version: Daemons are daemons, whatever you call them, nurglings, bloodletters, daemonettes...they are just minor daemons now. Bloodthirsters, Lord of Change, etc...just a major Daemon now.
Plague Marines, Thousand Sons, Berserkers, Noise Marines...all simply troop choices now.
I dunno. I think it screws up people wanting to make a pure Death Guard Army or Wold Eaters, or Word Bearers army a bit...but then...it doesn't.
Take your Plague Marines as troop choices, take your HQ and model him up as a nurgle guy, take possessed nurgle-looking guys and nurglings (lesser daemons) and you have a Death Guard force...and you get more choices now for Fast Attack and Heavies too.