To understand why developers and designers hate meetings and interruptions, you have to understand the difference between a maker's and a manager's schedule (as Paul Graham observed in his famous essay on time management).

People who create things (designers, writers, developers) operate under a maker's schedule, which is completely different from a manager's.

Managers can neatly divide acitivities into 1-hour blocks. They have appointments throughout the day, and they can change them on the fly. They can timebox every task and block of anywhere from 30 minutes to several hours for it. If something comes up, they can easily change the schedule (plus they don’t sacrifice any productivity while doing it).

Makers don't have this luxury. They can't divide their work into discrete 1-hour units; they need at least half a day of continuous work to get anything done.