I disagree with the numerous claims that Giant/Ant Man would undermine the suspension of disbelief. Excluding the Asgardian Element, the Hulk is far more unrealistic than Ant-Man. The whole notion of the transformation and how it renders him indestructible is well past the realm of possible, as well as having an infinite reserve of energy. With Giant/Ant-Man, he is still mortal and has far more threats posed to him by decreasing or increasing his size.
With that said, the general audiences that see these films have already signed a contract with the creative team: they know that the films are past the realms of realism, and are in the fantastic. But, as a compromise, the films are grounded in some form of reality that is on the far border of it. Truth be told, the entire notion of the superhero is the antithesis of reality: it's an escape from reality. And if someone goes to the film and is upset that it does meet their standard for measuring everyday reality, then they are a moron. Viking Gods, men in robotic armor, soldiers with super regenerative abilities, and unstoppable green beachballs cannot be successfully grounded in reality (if someone tries, it ends up becoming irritating, like the one chap who asked Grant Morrison who inflated the Batmobile's tires.) However, since they are grounded in fantasy, the fantastic elements can be downplayed or subdued, but at the end of the day, it is still the opposite of reality. If there is anything to be gleaned about modern audiences, it is that they enjoy the fantastic: there is a reason why the X-Men films have been doing quite well. People lap up the fantastic.