Why is there so much opposition to a manufacturers procedure??
I'm not sure that is quite correct. It's a very sweeping statement. It is a considerable change from the 'manufacturer's previous procedure'. This is not the first time the manufacturer has made significant changes. If it was OK before what has caused such a large change? I've asked Boeing pilots about other changes they've made previously to their QRH procedures and received very vague wishy-washy answers.
It's not an opposition it's a cry for information and understanding. Nowt wrong with that; it's what pilots do.