I think part of it is that the cost of messing up and having an undetected design fault in deployed hardware can be so huge for the big players. The big player

I think part of it is that the cost of messing up and having an undetected design fault in deployed hardware can be so huge for the big players. The big players are where the EDA vendors make most of their money and so derive their mindset. You make money by being reliable, and the easiest way to be reliable is to be conservative. Once the design process works, don't mess with it in case something breaks.