That would be rather a fault of how TMP did it but not a fault of the principle.Isn't re-introducing the same as introducing for someone who hasn't seen anything of it?
No.
Introducing characters generally requires that you give the audience a reason to give a damn about them. ST:TMP doesn't. It assumes familiarity.
Perhaps, but we're talking about TMP and the practical issue of whether those opening scenes would mean anything to newbies. Like Dennis said, the movie assumes that we already know and love these characters.
"Look! It's Bones . . . with a beard. And just as cranky as ever!"