To be honest the Inquisitor didn't get that much spotlight in terms of story either. I mean we done "cool sh*t" but it wasn't the previous two games where you got some backstory to their life before the breach etc. I'd say all the focus went on the environments and exploration.
While I agree that Cass etc were also plot heavy in terms of their link to the main plot, I disagree with you about Varric. Varric is one of the catalyst for half the crap going down (the red lyrium, Corypheus, etc) they just didn't bother to implement him enough into it beyond him occasionally feeling guilty for it and blaming himself, lol.
I still find the IQ much more focused on than the previous protagonists in the terms of overshadowing the companions...well besides maybe Hawke. As you said earlier you loved how Alistair was so tied to the plot and then someone else pointed out that Morrigan was fairly represented as well. I can only speak for myself, but I never once felt like my Warden was being shown up by Alistair or Morrigan. Maybe it's just a personal preference of mine, but I really don't like seeing a story focus more so on one character and let the others rot in the background.
Mmhm DA:I did seem to focus more so on the immersion of the world in the terms of gameplay, not the narrative.
Ah thanks for reminding of what Varric actually did in DA:I, as in blaming himself and what not for past events. Other than that...I saw no significance in him and I really lost interest in him about the time I met Sera...who has even less plot significance. I loved DA2's Varric, this one...meh...at least for me.