"We want to limit the length of a review in our application to 140 characters, because we may want to use SMS at some stage. That's a tiny change, right?"
Wrong.
There are no tiny changes when you're committed to delivery quality software.
How design and development are inextricably intertwined. I'm positive Jonathan Ive didn't design the iPod in a room by himself, but worked with engineers to push what was possible and find the best way to make the technology work for the design instead of