I live in thornton and as with most suburbs it has the same issues. I still run a couple errands each week on a bike since it is a nice way to break things up. I don't keep these many accessories on my bikes.
My garmin comes off easily and everything else is stashed in a messenger bag. With gas prices being what they are and the weather being awesome I do not understand why anyone would poo poo running errands. Plus, it is fun and an easy way to throw in a bit of different riding to mix things up. My bikes aren't exactly cheap but I lock up in safe public areas. Still, I need a better lock and a bike more appropriate to run errands with. I am thinking my next bike build will be something along these lines. Maybe an xtracycle on a MTB frame. Running errands is fun! I'm not saying your reasons have no merit. Just that it is another easy to enjoy cycling. Plus, I still have my van for when I am too tired or the weather craps out.
Too each his \ her own.