I was under the impression that you do a masters if you have a specific career in mind, due to the fact they are often very specific.
For example, we were given a few options to continue from animal science such as animal welfare, animal nutrition, equine psychology etc.
The research sectors involved in the animal indistry won't even look at you unless you have a masters and/or a Ph.D.
But that is VERY area-specific. I have no idea about other areas.