I've spent a lot of time hiking and backpacking. I've also had to walk five miles home (that's about 8km for those not in insane countries that start with "United") when buses or trains were cancelled due to weather.

I absolutely refuse to buy a backpack without a hip belt of some sort, because while you might not really need it for the five-minute walk from the bus stop or train station to the office, that changes when you're carrying it for a two-hour walk in the snow.