I think Rick makes some good points that perhaps being the defending player does make the intel from replays more important than when on the attack and of course if you have secure flanks and good LOS along your line that would also make replay intel less vital.
OJW also makes a good point that perhaps we do receive more detailed intel than we should having our "god like" view of the whole battlefield.
My POV is that if you don't watch replays and your opponent does, you do so in the knowledge that you are giving him a advantage of varying degrees depending on the scenario being played, not saying that it is wrong as everyone is entitled to play these games as they see fit.
I am in Rick's S14 campaign game and I timed watching a replay at 14 minutes, some people will say that is 14 mins of my life I will never get back!! LOL