That kind of thinking helps ward off mediocrity. Whenever I deal with somebody in my company, I really hope they think their work is important and I appreciate it in a positive way, even if their work isn't important and I'll only notice if they fail to deliver (in which case it will just set me back a week.)

Having a realistic perception of your own importance leads to depression and to performing at the bare minimum necessary to stay employed. I don't bother much with reality anymore; I prefer sanity and success to reality ;-)