As industry insider Psimet2001 points out in this previous post, all the arguments defending hookless ignore the fact that hookless rims for medium- and high-pressure tires disappeared from the market in the 1980's and reappeared only when carbon rims came on the market. As he notes, the same manufacturers that sell hookless carbon rims continue to produce only hooked versions of their aluminum rims. Why were no hookless rims manufactured for 40 years?

Edit: here's another post from wheelmaker Psimet2001 on the topic. That previous thread on the topic of hookless has a lot of good info.