I don't think it's a matter of helping or hurting, it's just a matter of style. Some coordinators like to be isolated and unfold the chess match from above, some want the feel of the game, look into the eyes & hearts of his players and the opponents fears, work the refs, and hear the crowd, etc... I think a lot depends on personality, and I agree with the point about assistants --the fit with assistants to accomplish/filter that stuff is crucial to the preference of booth or field I would think. And overall it's the fit to the identity of the team.
As far as seeing everything the sponsored-by-Microsoft tablets give real time aerial views now anyway. As to the original mention of Martz, seems like he ended up an on-field convert despite his better success coming in the booth?:
http://usatoday30.usatoday.com/sports/football/nfl/2007-12-26-playcallers-sideline_N.htm
"Detroit Lions coordinator Mike Martz is also a sideline guy. "I was up in the booth for the preseason last year and, at first, I was excited about it," he says. "But then I hated it. I couldn't talk to the quarterbacks the way I wanted. 'Tell Jon (Kitna) to …' I said, 'Aw, to heck with it.'
"On the sideline, you get into the feel and emotion of the game. I like being on the field more than I thought I would."
