Happy users, faster growing userbase, more e-store revenue, higher click-through rates, lower latency, better quality-of-experience, or more 7-day-returning users can be more important financial incentives than bandwidth. Humans are more than thousands of times more valuable than a computer.

When image quality and observed latency are at a level where users don't care even subconsciously (say, images look like camera originals and load in 100 ms), then bandwidth cost optimization may become a good 2nd objective.