A couple of other thoughts-some people have mentioned start-up diagnostics.
PRAM resets can sometimes take longer than someone who has never done one realizes, and the chime is the only real clue that you've actually done it. In fact, when I write up how-tos on older Macs(we have some at work running legacy hardware) and put in a diagnostic section, I always have to specify to keep holding the keys UNTIL you hear a second chime.
Many other boot options-like boot selector-have to be done before the chime. Again, it serves more of a function than just adding to the Mac experience.
The PRAM reset is a good point. They will probably remove that ability next so everyone can just bring their macbook watch to the genius bar so they can tell you its obsolete and hand you an ipad pencil to use with your watch so you can message scribbles to people.