User blog comment:James12708/Possibility of a Mass Effect 4/@comment-86.173.242.58-20121213224400/@comment-5491419-20121213231835

The problem with using Garrus (or any squadmate) is that they might not be alive for everyone. You can choose not to recruit Garrus in ME1, and he can die in both ME2 and ME3 depending on your choices. They would have to ignore past player choices, which I think would make a lot of people angry.