I think that it's muuuuch easier to downsize when you commute by car v foot / public transpo. I carry water with me everywhere it's just usually in my car (when I'm running errands) or my in work tote.
Absolutely. It's a catch 22 -- you have to carry more when you don't travel by car, but because you're walking more, you want to be as light as possible! Sometimes I'll go with a smaller bag but carry the water bottle and other extras separately in a small shopping bag. But then I get tired of carry two bags and go back to the big tote. First world problems, I guess!