If for no other reason then to help verify an officials accuracy and field vision when making calls.
Hypothetically speaking, lets say everything was determined through the eyes (or head Cam) of an official at field level as you suggest. Although all other camera angles at different elevations may expose something missed by an official. The determination or outcome would be equally balanced on both teams IMO.
The way I see it often times a penalty occurs away from the play. Does it hurt the game of football from an entertainment standpoint if missed infractions are equally balanced?
Myself personally, I think not...