Why would Keystone remove egress windows from newer models?

The updated rule does answer (somewhat) why older models had the egress and newer ones don't. It sounds like it creates something of a loophole that let's them get away with not putting that bunkhouse egress.

But again I still wonder, is it that much cheaper to put in a slide window instead of an egress? You're still putting in a window, I can't imagine one is that much cheaper than the other that it's worth the manufacturer changing the design.