Well I had no problem with the violence in Deadpool. Again though, Logan was way more violent than Deadpool. Furthermore, I don't think it needed to be that ultra-violent. It doesn't mean you have to go every bit as humanly possible to make it excessively ultra-violent to tell the story. It seems that was their main aim in this movie. I think telling a good story is more important than violence and action-destruction--just for the sake of violence and action.
Because this movie wasn't just rated R, this was taking the R rating to the next level in terms of the violence. Having said that though, I know there are other films that are even more violent, but most of those movies are practically just violence-porn. I'm not saying though that the story in Logan wasn't good, which it was, but I really think the violence was definitely over-the-top and unnecessary at times. Showing the decapitated head roll over for instance. More than that though. The child though...if you're advocating that it needed to be more graphic and violent than that, then I think that's actually mental. Was it not violent enough already?
I had a problem with the extended cut of "The Wolverine" being rejected a PG-13 rating by the MPAA because it was considered too violent, hence it would receive an R rating for the theatrical release. Unless it also had to do with the two additional times Logan said "f**k". Personally, the extended cut wasn't that violent to me.
Deadpool was rated R and didn't go that far with the violence and didn't make it the central focus. In other words, I mean it wasn't action-porn in spite of the R rating. Logan though...well.