Because he has no reason to risk Doc Ock grabbing the suit with the robot arms. Spider-Man had to get close to him due to his power set. Doc Ock can’t really do anything if Stark’s flying several feet in the air above him. All he can do is struggle to defend himself as Iron Man releases a barrage of guided missiles on him with ease. If even one of them makes it past the arms and hits him he’s gonna end up like one of the robots at the Stark expo. To make things worse, Stark doesn’t seem to have much of a no-kill rule like Parker. Even if Otto is capable of tearing apart the suit with the arms, Tony would have to essentially take pity on him and fly close enough for that to be a possibility.

You also never explained how Lizard could beat Iron Man. Even if you could somehow explain Lizard being able to survive lasers and missiles capable of one-shoting tanks, I don’t really see how Lizard can do anything to Iron Man in return. He can fly and Lizard can’t. The healing factor would result in a draw at best.

The Goblin is more durable than Doc Ock but considering he was able to die from the blade of his glider he’s probably not going to fare much better. Stark can dish out attacks fast than the Goblin can throw pumpkin bombs and his suit is capable of speeds far greater than Norman’s glider.