We are trying to pull off a very difficult balancing act with developing a new game and supporting an old one at the same time. Pretty much no one does that. Most large developers simply release games, support them for a month at the most, and then switch to new paid content regardless of the state of the game. We are however trying not only to patch up major issues, we're working on improving things that generally work - and we're doing that for free seven months after release.
We are doing that by trying to parallel tasks as much as possible and improving CoD while developing a sequel.