Well, technically, Angel Investigations didn't move to Wolfram & Hart, it shut down so that Angel and his crew could take over the evil law firm. Angel and the others, I believe, missed the entire point that the Senior Partners actually accomplished what they had been working for all along. They eliminated their biggest single enemy. It took Cordy having to almost literally beat Angel over the head with that fact before it finally sunk in, and I seriously wonder if Joss had planned to string the deception out for at least the end of Season 5 and on into Season 6 before bringing them to that realization. The last six or seven episodes seemed to me to be kind of rushed, attempting to reach a workable ending at Season's end due to the unexpected cancellation. At least it seemed to me that that's what happened.