It means that spock was the only character that had opportunity for development and growth, and no-one else gets to share in that.

This is true. I do think they did a fair amount with it in that respect, though, and he’s now pretty firmly on the trajectory he needs to be on to line up with his TOS characterization. And I’ll give full credit to Ethan Peck for selling his barely-restrained panic attacks (full-blown meltdowns by Vulcan standards, I’m sure).