I wouldn't really call it a pain just that some people don't have the patience to swap discs. I've done it plenty of times with LA Noire and Battlefield 3.
As for the 20GB update, that is a really hard blow to a lot of people, me included. Everyone is expected to download the update but not everyone can do that. All of us on limited internet data allowance will have to spread this update out over a long time e.g downloading 2GB a week. And that leaves me with a ten week update. Thank you 343, thank you....