Wrong. If you happen to get to a branch at 8:55 am to use the ATM (assuming they open at 9:00), you'll see a line of people waiting to get in. Are they all just old people who don't know any better? A quick inspection will show that they're not.
One reason I've gone to one was to get a bunch of $100 bills to pay for my puppy at a breeder. For some reason, breeders tend to insist on cash. I suppose there are less legal reasons to want $100's, but I wouldn't know about those :)
Continuing with "choice of denomination": if you operated a retail business, or you were having a garage sale and you wanted a whole lot of variously sized bills to make change, you might go to the bank.
Turning in coins? Lots of stores have coin machines, but they take a commission out if you want cash and not store credit.