When Warner Bros. Announced that their upcoming Batman V Superman: Dawn of Justice was getting an R-rated 3 hour long directors cut DVD, many assumed that it had more to do with Fox's Deadpool success than something beneficial for the fans.
DEB: "Online, everyone's like, "Oh, they're doing an R-rated in reaction to Deadpool," and you're like (laughing), "We didn't just shoot it last week, and we also didn't edit it last week."
ZACK: "The why of that is [the DVD version] is a half-hour longer, and some of that additional material is some of the stuff we took out for the rating. I was like, "Cool, I can put it back in for the director's cut." There was nothing by design. This was the material I just put back in, and then when [the MPAA] looked at it again, they were like, "Oh, now the movie's rated R." And, by the way, it's not a hard R. There's no nudity. There's a little bit of violence. It just tips the scale."
These things are typically approved way ahead of time, so no I don't believe that right after Deadpool's huge payday at the box office, there were tons of execs scrambling around trying to slap an R on everything in the office. That said, I'm sure it made the studio much more confident in their decision.
It's basically Snyder putting back in all the deleted scenes, which equals out to a new 30 minutes of footage, as opposed to the film cut of 2 and a half hours that will display in theaters.