I have been commuting by bus for just under 14 years.

Everything I carry in my backpack I've used at one time or another. You're carrying more than needed.

- Outerwear appropriate for walking at least a mile outdoors in the local range of weather

Well, you should be WEARING that right?

- dress shoes

I don't get this. Why would you carry dress shoes?

- iPhone Charging

Yeah, everyone with an iPhone needs a LOT of backup power options

I'd add:

Bandanna, Chapstick, Small sunscreen, $100, Small Towel. The towel is no joke - the small towel I have get a lot of use - I put it in my lap if I have tea to drink, I roll it up as a pillow, I wrap fragile things in it. Very handy.

Standardize your flashlights to AA or AAA batteries, match your external USB charger. Carry Lithium spare - much lighter.