It helps immensely to look at your opponent in certain situations when you are expecting a move, let’s use Ken as an example:
You’re right outside c.mk range, and both characters are just waiting for each other to do something. If you’re looking at your opponent’s pixels instead of yours, it will be easier for you to punish when they throw out a move that’ll extend their hitbox so your c.mkxxsuper or raw super will hit.
Or with ryu during any denjin setup, it is more beneficial to look at your opponent since your own character is static.
That’s not saying that you should always play like this though, since looking at your own character has it’s own benefits as well. Like right after ken sa3 knockdown you should be looking at yourself to position for an ambiguous setup since your opponent’s position is static. Same for akuma’s sa1, or any other super that causes a hard knockdown.