Contrast that with Peter and Gwen's situation. There was absolutely no reason for Peter to demand a smooch (the smooch) from Gwen. No script, no paycheck on the line, and it was far from the only thing Spidey could have done to ham it up in front of the cameras. In fact, considering that up until that point, no one besides MJ was aware of that kiss, it was less effective that some other things he could have done. It was used in the movie in the context of Peter becoming somewhat callous, so how is it inconceivable that audiences would perceive it that way?