I think it depends on the type of mission.
In a mission with set and static objectives I don't care if most of the map is empty.
You move in and do your mission and then move out, filling the map with other stuff is usually pointless.
I have done this mistake many times myself, adding stuff everywhere "just in case".
To my disappointment I have never heard any player appreciating it, maybe because they never found out.
I guess very few players are interested in this realism/discovery/RPG factor.
In a very open mission like "Manhattan" however, I really want to feel that the world is alive.
Immersion demands that stuff happens everywhere, and that you can go anywhere.
Thankfully the ArmA2 modules solved many of these problems, I think.
But in OFP and ArmA it was a constant pain to achieve the same thing.
I think there are other and maybe more severe "realism killers" as well.
In MP I loath any respawn other than revive or group, the rest are arcadish and boring IMHO.
Group respawn at least lets you continue as another team member, a good realism/gameplay compromise.
The warfare style "build your base in 30 seconds" is also an immersion killer.
If story or practicalities don't work as in real life or very close to it, it really kills my fun.
Guess I'm a stiff realism fan, but I wish that every mission simulated reality as much as possible.
I wish that BIS at some point will implement editing commands that override the difficulty settings.
Anyway, those are my thoughts.