The following summarizes Matt Cronin's report on Roger Federer's press conference on Thursday, March 11 at Indian Wells. Cronin's service is by subscription so I can't link to the article but I can summarize. The presser is Roger's first since the Australian Open.
Roger feels he committed too soon to play Davis Cup and since he's not even sure he really wants to win the Cup this year it's not a priority for him at this time. His priority is his long term career - he wants to play for many more years - and the decision came down to playing with a little pain or resting and ensuring his future. If he felt that his career was going to be over soon he'd be more concerned with Davis Cup.
Swiss Davis Cup captain Severin Luthi will continue to work as a coach with Federer.
Federer feels he played a great match for four and a half sets in Melbourne. He felt his opponent was tired and that he didn't take advantage of the situation. If his serve had been better he feels it would have set up his baseline game and he would've been able to execute his game plan. Because of this he felt under pressure at the end.
Roger feels he lost Wimbledon during the first two sets not the last one.
Note: If a complete transcript is released I will publish it in it's entirety.