Hot sports opinion: you don't need a caddie.
When it comes to playing the course, it's all right there in front of you. There's nothing particularly tricky about the course if you've got a rangefinder and an app like The Grint on your phone. It's also not an especially hard walk. Aside from the climb up #6 I don't remember any other spots where I was really wishing someone else was dealing with my bag (you can get a pull cart).
As far as the camaraderie and all that, I've gotten caddies probably twenty times. Always at nice, expensive courses (Pebble, Scotland, Ireland, Bandon, etc). I'd guess my W/L/T record is around 3-4-13. I've had a few that were AWESOME, a handful that kinda sucked, and the overwhelming majority were just... fine.
Anyway, there are tons of stories out there about awesome caddies who really enhance your experience. But there's also a chance you're gonna spend a couple hundred bucks to spend five and a half hours hanging out with some dude whose company you don't enjoy.
If you get a caddie, I hope it's awesome. I'm not saying DON'T do it, I just don't think it's a must.
Also there's a decent chance that someone in your group has a caddie and you'll get a chance to BS with them waiting on tee boxes and stuff.