A Geeky Viewpoint

What's interesting here is "nudity" and the uproar it's causing on the interweb.

Okay, let's go back a moment to the original X-Men movie in 2000, it also was PG-13, but simply for "Sci-Fi Action Violence" (which today would just result in a PG rating-post 2003). In X-Men United (2003) the explanation included "Sci-Fi/Action Violence, Some Sexuality, and brief language".   In X-Men: Last Stand (2006) the explanation contained "Intense sequences of Action and Violence,  some sexual content, and Language."

Sequences of sci-fi violence and action is simple enough to understand in the context of this movie, some suggestive material is interesting, but we have seen the picture of Younger Magneto kissing Younger Mystique.

Simply using one bad word ie "You are a cold hearted Bitch" is enough to get a PG-13 rating in today system.  

Why the uproar?   Nudity!

The use of Nudity in a non-sexual situation, ie usually a women's breast or someone's butt, is another mandatory situation that gets you a PG-13 Rating.   To not get an R rating you cannot combine nudity and a sexual situation, so you cannot have a naked backside climbing into steamy shower with sexual dialogue. 

Okay before everyone worries and tries to cover their children's eyes, last year, April 2013, the Motion Picture Association of America (MPAA) updated their descriptors on why movies were rated the way they were.   Mystique, changing from blue form naked women to dressed other would result in this Nudity being described.   Without seeing the movie this is my assumption.

The movie clocks in at 2 Hours and 10 Minutes.  Equivalent in length to X-Men: First Class and The Wolverine and X-Men United.  However it is substantially long than X-Men and X-Men: Last Stand.   None of that seems so important until you realize the both Bryan Singer and Simon Kinberg have been making the rounds talking about the scenes and stories that are not in the film.   The entire Rogue story line of over 10 minutes has been dropped, the young Quicksilver and Scarlett Witch scenes, additional footage in several fights..    Supposedly there isn't enough cut footage from X-Men: Last Stand to add two minutes to an extended edition, yet the Director, Writer, and Producer (Lauren Shuler Donner) is suggesting there might be 30 plus minutes of finished film.   That's Lord of the Rings extended length.   The entirety of The Wolverine Unleashed was 12 minutes and 4 minutes of that was a single fight sequence that just doesn't work.