I carry it regardless. I carry it because I have a commute of almost an hour and a half, much of it on a train, and I like having my Kindle and my sunglasses and other things, but don't carry my laptop to/from the office (thus no laptop bag). So I have a small shoulder bag that I put stuff in and bring with me.

So any time I'm going to be out long enough to have to theoretically carry full kit for my phone (in a hypothetical multiple-dongle world), I'm also going to have that bag with me, or some equivalent object for carrying things (i.e., extended outings not involving going to work), and not have to stuff everything in my pockets.

Apparently this is weird enough to be downvoted into negative-score territory.

Out of interest, is there a noticeable difference between the USA and Europe for bag use? Here in the UK, a bag is sensible and I could imagine going to work without one (for my lunch, spare USB cable, iPad etc).

I had never thought of it being a significant cultural difference.