There are no critters, monsters, beasts, insects wandering or attacking or taking a #2 on any planet I have come across. Why? There should be random creature spawns on planets so you never know what you will encounter.
It would be very nice to have some possible challenge wherein one can decide whether or not to avoid, investigate or defend against the fauna of a planet.
Heck, it would be awesome to every once in a great while just happen across some crazy difficult to deal with beast of a monster that could be considered some form of Boss on one of those planets. Something that can make one of those missions suddenly go a different direction.
to be fair, the planets in this game are typically not any more or less populated than the TV shows (all of them). If you think about it, it's pretty faithful in that respect.
IMHO, given the variety of planets and randomization that goes on, I wouldn't want to see them incorporate random wildlife until they could do it procedurally. Seeing the same reskinned model on 100 different planets would be pretty atmosphere breaking. If they could create the monsters and textures procedurally I would be all for slightly more populated planets, even though the current state is very faithful to the spirit of the shows.