To be honest I've always thought it was kinda cool
to see Spidey or Batman or Iron Man without their masks on. Somehow it makes it feel a bit more "real" when you see the actors actually wearing the suit.
Plus it's kind of a necessary evil at the end of a movie when you really NEED to see the actor's emotions (since there's no thought balloons or nonstop narration to explain everything). Especially with Spidey, who's completely covered up.