Roy 99 percent of bathrooms on new builds are plasterboard wake up and smell the coffee, you've probably had one bad experience and now you seem to think it's the work of the devil
If he wanted to dry line it you shouldn't need to remove any plaster unless it's falling off, unless the walls are in a bad shape you should just be able to remove any hollow stuff patch it and reskim, anything else is extra work that you shouldn't need doing
get a pro in plastering looks easy if i had a penny for everyone who said `i do a bit` id b a millionaire it depends how fussy u r it is an art when the light catches it youll notice the difference