That is a good point. But it's not that I think it's sacred, just that it was so memorable and significant that you can't just throw 100% of it out and expect people to go along with it no problem, unless you have something really good to offer in exchange, and Byrne certainly didn't.
Morrison starts his run with some extreme direction shifts, but he does it by showing you a lot of exciting new things and asks you to give it a chance to be better than what came before.
Byrne strips out the horror and pop psychology that had become synonymous with the comic, but he doesn't offer anything new, and he doesn't do a good job of showing you why the characters are better off without it. It's just stiff Byrne dialogue and dry Byrne plots like always.