I've been thinking a little about this lately because I've been playing a game (Here) which has only four wandering monsters per dungeon level. It also doesn't have a place to check which level table to roll against, so not only is the number limited, the particular table is predetermined.
Simplistic? Well, yes.
It's not as dreadfully boring as it would seem to be in comparison to the elaborate wandering monster tables I'm used to - anything from 1d12 to 2-20, and checking which table to roll on as well.
I wonder if using more limited tables would actually give a dungeon or wilderlands hex more verisimilitude, because players can count on a few, regular, repeating enemy types. After all, if you're only rolling one, two, four times on a particular level, there may not be a pattern for players to recognize. Random may actually feel, well, too random to prepare for. What do you think about, say, a wandering monster table with 6 entries? 8?