Actually some time ago I, like you did, asked myself the question about practical aspect of Chronograph Complication. I haven't found any reply until I read in one article the following words: "DOCTOR'S WATCH". It was Evrica! Really, doctors, lowyers, personal teachers work on hourly basis! If you have to measure time precisely when you work with another person you are to have chronograph.
Golden/platinum chronograph tells your potential client your level of hourly payment, of course
Every complication is useful but not for everyone.
Best wishes for the New 2012 Year!
Dennis