I finally saw Deadpool after hearing all the positive feedback about the movie. Clearly this is one of the best movies I've seen lately as it is a complete change compared to any superhero movie created so far.
Deadpool is not the usual superhero movie and was R-rated for a good reason. Sex, violence, curse words, the movie has everything you wouldn't expect in a Marvel movie. And it is a good thing since the success of Deadpool showed that the audience was responsive to that kind of movie and will go to theater if another one is made. For Marvel, and even DC, Deadpool opened the door for other more adult comic-book to be adapted.
For example, the third Wolverine is said to be confirmed R-rated. This decision was probably taken as a results of Deadpool's success at the box-office and it's probably a great news for the franchise. The first two instalments of the franchise were nothing but memorable and could have benefited from a treatment more true to the violent nature of the character.
There are however some downsides to the Merc's success. The movie was an exceptional hit, clearly, but it was maybe just an exception. Deadpool relied on a well-established comic-book character, an A-lister completely invested in his role and a sprawling marketing campaign. It worked very well, to say the least, but it won't work for every character.
Studios can't start to think that any R-rated superhero movie they'll made will be a major hit. In Deadpool's case, making that kind of movie was staying true to the character but it isn't the case for any superhero. I can't imagine Captain America or Superman turned into R-rated movies, this is absolutely not what those characters are about. There is a substantial risk to see more and more unnecessarily violent movies, only because it's trendy.
Companies mustn't lose sight of what made Deadpool successful: a funny and unpretentious anti-hero, made by passionate fans while remaining true to the superheroes "code". It's not the rating of the movie or its violence that made it work.
I'll leave the last word to James Gunn who probably described the situation better than I can:
So, over the next few months, if you pay attention to the trades, you'll see Hollywood misunderstanding the lesson they should be learning with Deadpool. They'll be green lighting films "like Deadpool" - but, by that, they won't mean "good and original" but "a raunchy superhero film" or "it breaks the fourth wall." They'll treat you like you're stupid, which is the one thing Deadpool didn't do.
But hopefully in the midst of all this there will be a studio or two that will take the right lesson from this - like Fox did with Guardians by green-lighting Deadpool - and say - "Boy, maybe we can give them something they don't already have."
And that's who is going to succeed.
Have a great day.