Most CoD updates were related to online issues stemming from millions of people playing simultaniously. However, CoDs issues can only be addressed after the fact, and they ARE addressing them. New Vegas doesn't have to worry about millions of users accessing servers all over the world. They have all of the software in front of them and they've made only minor tweaks to a nuclear glitch bomb of a game.
Yes, Activision may have more money coming in from this title, but that's not what Zenimax is competiting against. They're competiting against profit margins. And if they want to maintain theirs they need to find a way to satisfy the customers they have now. We may (will) not be here next year.