I've been taking a backback to/from work ever since the USAF figured out we actually carry stuff around sometimes (duh) and allowed backpacks to be carried/worn in uniform. "Stuff" is right. My backback currently holds a 1.5" 3 ring binder full of professional reference materials, 2 fairly thick folio folders with retirement paperwork, an electric razor and toothbrush/toothpaste in case I get stuck on duty more than 12 hours (happens), 2 pairs of glasses (reading and computer), some random breakfast bar thingy in case I get locked down in my workplace (happens), some of that little squirt flavoring for water, a book of study stuff for professional pilots for after-retirement, and a book on parenting 'cause my kids are total spazzoids. I also put my lunchbox in there 'cause my shift is 8 hours tied to a desk with no breaks except toilet runs.
Can't carry that in my hands or pockets, and a briefcase big enough to carry all that would be stupidly large/heavy. Shoulder totes are... well, shoulder totes I guess, most look like the diaper bags we've been carrying around for almost 8 years now.
So, backpack.
If I get hired by the airlines, I think the cool kids use a professional sized roller carry-on plus a smaller detachable bag sized for headsets, tablet, etc.
