I carry the direct opposite of a tactical bag. It's an L.L Bean medium zippered Board and Tote. There is room for my sunglasses, a note book, pen and my cell phone.
Actually, I have an LL bean tote, usually for going to the beach, and really enjoy its capacity, simplicity, and durability. It tends to be a bit heavy, but for short walks from hotel or car to the beach, its nice.
This is my 'messenger bag' if I absolutely MUST have a bag with me in the city. Genuine WWII army surplus (and used by me in the Air Force). Cost in a surplus store is a few dollars and the patina comes free with it

Measures 12 x 9 x 4 inches and can hold more than I would ever need. It weighs next to nothing when empty.
That definitely won't be mistaken for a purse! I like the durability. You mention that its light---how much does it actually weigh when empty? A military bag is a useful solution, but I'm not sure its for me; I did not serve in the military, and the only military gear I own are heirlooms from my father and grandfather, who were in the navy and army...if I used military gear, I'd feel like a poseur and somewhat insulting to the people who
did serve in the armed forces. Otherwise, your suggestion is very promising.
I am thinking a full briefcase for me is too much, but I too would like a general carry-all bag for when I run errands or will be out and about a city walking all day, such as NYC. I have backbacks and they are great for airports but I don't know that I want a backpack all day. Then again, a full carry briefcase and even in leather would be too much. I have seen some filson messenger backs on Ebay that look good, and then for the price, the LL Bean messenger looks good. There is a Mills canvas that uses like sailcloth but at $170 or so, I would spend a little more and get a Filson.
The cotton and canvas bags that have been mentioned by you and others in the thread look great and clearly aren't a purse. While the aesthetics are good, it seems they are often large and relatively heavy; one of the linked leather satchel bags actually weighs more than my main luggage :\ Hopefully I can find a minimalist bag.
I don't think there is a perfect answer to this question. Different travel situations require different stuff and one bag will not fit all situations.
4. Get over caring what anyone else thinks.
7. If you need [to carry] more than stop worrying what anyone else thinks.
I wish you luck and please let us know what you end up getting.
I'm starting to agree that there just doesn't seem to be a perfect bag with aesthetics, minimalism, masculinity, security, durability, and ease of use for every situation. The bolded parts of your post really resonate with me, and i might have need to simply pick a bag that comes closest. I'm considering something like this in Deep Blue:
https://www.tombihn.com/collections.../collections/tote-bags-and-shoulder-bags/products/side-kick?variant=54885618631 It meets all of my needs, even if it doesn't appear overtly masculine. 9.6"x7.5"x2.8", 9.4 ounces, good interior organization yet plenty of open space, and still slim...made in the U.S. from durable ballistic nylon.
Perhaps 'masculine' isn't a look or a feeling, but instead simply requires having the proper tool (or bag) for the job, and being mature enough to not worry about others' judgment.
Of course, I'll keep a leather briefcase for the office, and heartier bags for outdoor recreation, but this may be the best bag for vacation usage.
Thank you, everyone, for all the comments. They've been enlightening, both practically and existentially.