Double-walled rim's what difference depth makes? Provided both rims are double walled aluminum, what advantages/disadvantages of having deeper 30mm rim vs more narrow 18mm depth?

EDIT: I am not Tour de France type of rider, not setting world record in speed, more of commuter, most of the time i am cruising in the city streets and sidewalks.
Used to think smaller depth rim has less weight and this could be advantage for cruising (not high speeds) compared to deeper heavier aluminum rim also its more flexible so it could be advantage as well for bumps etc?
P.S. I do have a 700c retro skinny frame bicycle.
Strength, and image of aerodynamics. A deeper rim is stiffer and can get away with less spokes or sloppier build than a low profile rim. Aerodynamic wheels have typically deep rims, and all deep rims get part of the glamour, even though bad design can make a deep rim just draggy as a low profile box section rim.