There's a hell of a lot more to being a round character than being sympathetic or scary. You can have completely flat characters who sympathetic or scary, and fully realized, three dimensional characters who are neither. This also applies to villains. A villain doesn't have to be scary to be an effective villain, nor must he be sympathetic. Being a three dimensional character doesn't have to have anything do to with how sympathetic your motivations are, and it has everything to do with how many layers of personality they have outside of the role they fill in the story. Perfect example is The Mayor of Sunnydale in Buffy The Vampire Slayer. His evil scheme? Make a pact with demons to built a town on top of a portal to hell to give demons a massive feeding ground, cover up and facilitate the horrors they inflict on the townspeople for 100 years, only stopping them when they might destroy the town (or world) all together, and ultimately personally slaughtering a few hundred high school seniors and their families on the day of their graduation. His motivation? Doing all of this would transform him into an all powerful, Cthullu-esque elder Demon-God. Totally selfish, evil motives and acts. But he was a three dimensional character, because he had hobbies, interests, mannerisms, outlooks, and a personal history that were very well developed and realistic.
And on the note of being sympathetic... a sign of a good writer isn't that they can make a character morally ambiguous enough to be sympathetic. It's when they can make a character who is a truly evil son of a ***** sympathetic. This usually happens by giving them humanizing moments. Not moments that paints their morals or motivations in a more ambiguous light, but moments that show that the character, alongside their evil schemes and deeds, is capable of human emotions and needs. I will use The Mayor as an example once again: He had a very loving, very nurturing father/daughter like relationship with his enforcer, Faith. This in no way effected or informed his plans, he had made them 100 years before he ever met her, although the one addition is that she would not have a place of power and comfort secured by his side when he ascended. And despite all of their sweet father/daughter bonding moments that made it very clear that they truly, genuinely cared about one another, the show created no illusions about the fact that he was an evil manipulator and she was a stone cold killer. But those moments allowed us to connect to the characters and understand them. The sign of a good writer is not generating sympathy by reminding us that the character is good, but by reminding us that the character is human (figuratively, if not biologically).
One I think someone willing to sacrifice an entire town to demons for perosnal power is a very scary character, you have non sympathetic villain, but the character should have a presence, some menace, should be threatening and terrifying or have some style, not be some doofus in pink spandex with a phallic shaped helmet. William Stryker in X-2 wasn't sympathetic, but he was scary villain, a symbol of fanatical hatred. Obadiah Stane, Joker, Abomiation and other such comic movie villains were not sympathetic, but still compelling.
Two how does any of this apply to the Wizard, how is he a 3 dimensional villain? Frankly he is not, there is nothing nothing to his character beyond being a snide jerk. Its a nice speech, but irrelevant if it doesn't apply to the characters we are talking about.
The problem with a Wizard is two fold, he's a forth rate Dr. doom clone and he's annoying. Dr. Doom has facets to his personality and goals beyond getting revenge on the Fantastic Four, does Wizxard have? And what's Wizard's motive, to defeat Reed Richards to prove he is the smartest man alive? Gee, where did I hear that before, maybe because its part of Doom's motive. Doom hates Reed because he blames reed for what hapened to his face, why does Wizard hate the FF again?
Wizard is also annoying, because unlike Doom who can back up his boasts, Wizard's boasts come off as nothing more then verbal diarrhea, he seems completely out of his depth when fighting the FF. Seriously why has he never formed Evil eight, because a genius would learn from his mistakes and try to not repeat them, Wizard forms Frightful fours, over and over again, thinking that will work this time, even though the Frightful four has failed every time. Also why he keep on putting Trapster on the team, instead of switching him someone more powerful. The Fantastic Four is one of the most power teams around and has some of the best team work skills in the Marvel universe and wizard seeks to defeat with a team that usually amounts to a bunch of street level thugs? Wizard even surrenders any sort of numbers advantage
Wizard is supposed to be a genius, but is written as idiot who is over his, head, all the time. He has ability as a inventor, but he is one of the worst tacticians in the Marvel universe and completely unconvincing as a FF villain. That's why he is a bad character.
*applause*
Moral ambiguity is exceptionally overrated.
But I never said a villain has to be sympathetic, I merely said its one way to make a character more multi dimensional.
When I said Wizard is not scary, that means something important, it means he lacks presence and menace and frankly is not a compelling villain at all.
I can find tons of villains scary on different levels, William Stryker from X-2 was scary, not because he had powers or was physically impressive, but because he represented something, fanatical hatred, the type of hatred of that causes wars and genocides. Not sympathetic at all, but still compelling.
How is Wizard compelling, what evil does he represent? Annoying, smug *****e bags?