On our recent first FP+ trip, I felt like there were fewer line cutters than on previous trips. Before FP+, it was a daily occurrence for us in line for a headliner like TSMM at rope drop: we would see multiple families where one parent would get in line with the kids while the other parent runs for a paper FP, then shoves their way through the line to catch up with their family. It's kind of sad watching families get super stressed out to save a few minutes in line when they could have easily just stayed together like most others did. The place where we still encountered lots of poor line behavior was the exit from pre-shows, particularly ToT.
My reaction to line cutters depends largely on their politeness. I can see them coming miles away, and being a large tall man I will just happen to be cluelessly standing in their way. If it's a single person and they are nice and say something like "Excuse me, I'm so sorry, I got separated from my family, would you mind..." then no problem. But if they touch me or try to shove past me without saying anything, I will pretend to be confused as to who they are and what they want, for my own amusement. The more angry they get, the more stupider I act. I might top it off by announcing "Heads up, VIP coming through!" after they have pushed past me, that really gets their blood boiling. The way I figure it, why should everyone waiting in line be grumbling silently, why not have some fun making the cutter's blood pressure go through the roof.