One should be at the bottom one at the top. I understand space on the phone is a premium but a second port would make the phone so much more usable. Wired headphones, flash drives, camera modules, speaker modules, keyboards, even connection to a TV, all could be used while charging. It's a shame it's not a thing, USB is extremely versatile port, but you only get one and it's used for charging half of the time. (I am aware dongles exist)
I never understood why space should be at premium. A phone does not need to be as thin as possible. 1½-2cm thickness is reasonable in my eyes, and would allow so much more ports and/or buttons. I would have use for 2-3 extra buttons.
The biggest pro of two opposing ports: you could always charge your device regardless of orientation. With just a port on the bottom charging while scrolling in the bed is often uncomfortable