I actually think the appearance section on apps is helpful for the player even if it's a game with PBs. Appearance is more than 'John has brown hair and brown eyes' -- it's also how a character dresses, whether they wear makeup or jewelry, their height and build (which are often not apparent from a PB's face, or which can be totally different from the PB in real life!), scars and marks and tattoos, their posture, how they carry themselves, any physical habits or tics (like biting their nails, fidgeting with their hair, anything that would be readily apparent to other characters), which can be really helpful to other players when you're scening. Personally, I really like using the appearance section to make comparisons and flesh out the character's gene pool a bit: 'John has his father's brown eyes and playful smile, but he looks more like his mother with his Mediterranean complexion and slight build.' It's also helpful for me because if I don't write it down somewhere I can easily check on it, I tend to forget whether that burn scar is on his left or his right arm. But maybe that's just me. :P
I also often like to include accent, manner of speech (soft/loud, low/high, slow/quick), and verbal tics or habits in the appearance section, since there often isn't a separate section for that and I think it's pretty important to know.