When stuff is the state of the art, then its "look" is nothing special, that's just what things look like right now. There's nothing inherently special about vinyl records in the 60's. But later, when tech has moved on, people will look back and see the old tech for it's unique qualities. Some people will find they like them as an aesthetic choice, rather than just accepting whatever the current status quo is. It always happens - there's no photographic medium in the history of the field that's totally gone out of existence. Hell I met a guy once who still makes albumen prints.
Add that those old cameras are dirt cheap, fairly easy to find, and much more convenient to use than other old techs (like medium format film, for example), and add a dash of nostalgia... Whats not to like?
I think that's totally reasonable. I always felt the same way while photographing events.
That said, you should pay attention, and sometimes you may decide to switch back to manual and adjust from the automatic settings and retake a shot, to achieve something specific.
Also, shutter-priority and aperture-priority can be a great middle option. I often did that for weddings, which are often in dark (sorry, "romantically lit") reception halls. I use shutter-priority to make sure I keep things at a reasonable place for hand-holding the camera, set my ISO based on ambient light, and let my aperture and flash float automatically to accommodate slightly different lighting in different areas. Trying to shoot "100% manual" just to prove I'm a "real photographer" would mean worse images in most cases.