I like the team aspect.

Originally, IIRC, caddies were first available to visitors to the course, to help them navigate around the course (and obviously cart a bag).

Obviously this quickly expanded to members as well (as well as the Tour).

With practice rounds, I think if pro's didn't have caddies, they'd make all the computations themselves. Then, on every shot, they'd reach into their bag, pull out their much-more-detailed yardage book, and take the time to read it.

Honestly, I think without caddies, the game would slow down at the professional level.