Remember that when disc brake came out, ALL the major manufacturers said that they were death-traps and Porsche and Ferrari refused to have them on their cars. Only getting their *sses handed to them by smaller, more nimble and innovative outfits caused them to change their minds... slowly...

People are just resistant to change that's all. A lot of tooling, time and emotion tied up in older technology. It takes a dramatic shift, such as major benefits, cost/weight, strength/weight, etc. before something's fully adopted.