That's a realism argument, but in game design I'm with
@Reynard: it should all be about interesting choices. So unless the realism finds expression in rules that cause interesting decisions, I wouldn't bother.
In this case the interesting decision could be time vs. treasure, or more explicitly the risk of a having an unexpected encounter versus the possibility of finding something interesting. Sure, the heroes can spend the necessary time to search the rough cavern floor (and here is where "and with only one of you carrying a flickering torch, that's going to be a challenge..." can add some realism-based flavor) but it's going to use time, and time comes with risks.