At the end of the day, biomed is mostly the (successful) creation of a university marketing department. It mostly is just the repackaging of stuff you'd learn in science, it's not like they give you a felt robe and you join some secret society where you receive hidden wisdom. If you're doing neurophysiology in science, they won't leave out the neurons or anything silly like that. You'll be getting more or less the same stuff.
I think the cohort is a valid point. Putting that aside, in science you'll find the same content and much more freedom.
It's a simple fact there are many more people in biomed (not to mention science) than there are medical school places for. People will lose out. Science allows you much more flexibility to do what you want, totally change track and (at monash at least) take a lot of electives.
The Biology subject we do first year is much better because it skips over plants and allows you to go a little more in depth with human stuff.
Some people wouldn't count learning as a downside
If its anything like monash (and i assume it is) it is really only a week or two out of the entire course. Just because it might not be necessarily useful doesn't mean it cant be enjoyable or important to learn. Same with stuff like evolution or animal diversity.