I like to carry everything I may possibly need and I hate bulging pockets so I have a couple of bags, one is a 25ltr back pack which I normally just wear with one of the strap's over my shoulder and the other one is much smaller, say 5ltrs which can be worn with the strap across the body but I just sling the strap over one shoulder.
Each to their own but I would never be seen with a bum bag, ever!
A bag is a bag, no need to call them man bag's, it just sounds like you are trying too hard to justify using one whilst being a man.
No one gives a hoot if you are carrying a bag or not but nobody wants to see bulging pockets which ruin the look of your attire. I'm 58 by the way but believe any man can wear a bag at any age.
Phone, organiser, glasses, wireless earbuds, keys, pen knife, touch,, water, gaffer tape, strong zip ties, gloves, ok those last few things I don't carry but if you wanted to you could!
Paul.