Also, the larger hex spreads out the load on the center of the wheel which makes it less likely to crack under more abuse than a 14mm hex.
I just changed my savage and aftershock to 17mm hex's last year because I was starting to spin 14mm hex's out of wheels. Gets old fast. I had run 14mm hex's for years without a problem... but as soon as I bought an LRP28... problems began! lol Stupid powerful engines!