Had a conversation with an acquaintance regarding his first jet type. I encouraged him to do a bit of flying without the automation. He said he didn't want to fool around like that in front of the trainer. It's not "fooling around", it's developing a skill. And if not with a trainer, then when?
Quite a different attitude to manual flying on this side of the Atlantic. While undergoing line training on each of 2 types, I was required to demonstrate at least one approach with no automation whatsoever. Obviously, I agree with the OP, that it's important in the sim, but it's even more important to do it on the line.