All of which is a HUGE problem on a multi-day hike.
Understand what your gear can and can't do. I have a really nice (Patagonia) backpack that I take with me when I go into town on the weekends and to work when I don't need a laptop. It is also great for going to the gym and for multipitch climbs where we are maybe ten minutes from a car. It is durable as hell and I can tie a small static rope to it if I am going to go up a chimney.
But it is tiny and it doesn't have a particularly secure top (draw string closure with a buckle). So if it is raining, I leave it at home. And if I am more than ten or fifteen minutes away from the car, I'll take my normal hiking backpack with me so that I can actually carry supplies and extra gear.
Does that make it bad? No, not at all. But it does mean there are some huge caveats to it.