Strongly agree on the first but thought Marcus was (though underdeveloped) too much of a "moustache-twirler."
I always thought Khan from the Wrath of Khan was a bit of a"moustache-twirler." An over the top one dimensional bad guy. That really isn't a criticism just more of an observation. Hollywood has many examples of clear-cut, black and white good guys vs, bad guys and in TWOK Khan was a simple bad guy.
I don't mind one dimensional characters as long as they are acted well and I think Weller did a good job with Marcus.