I have to agree with you, I have what most would consider to be an incredibly foul mouth but I don't understand why people don't have respect for others and their kids. I would never start throwing the F word out around kids. Like others have pointed out, I think society in general just doesn't seem to have a lot of respect for others any more.
I was at Epcot in 2013 and myself and two friends were in the single rider line at Test Track waiting to get on when an older man suddenly started waiving his wife and daughter (who was at least 17-18 years old - not a small child who may have needed a bathroom break) to join him in the line. Normally, I'd think no big deal but it was a very busy day and we'd been waiting in the single rider line for quite some time so one of my friends pointed out that they were cutting. He turned around and said they were his family and they were joining him on the ride so my friend quickly pointed out that this was the single rider line and they wouldn't be able to ride together regardless. This man, apparently holding an award for world's shortest temper lost his mind and started saying he would "beat the @#&% out of us"... I mean, shouting and raising his arms- the works. Luckily a lady in front jumped in and alerted a cast member who separated everyone because this guy had started threatening to get violent. Of course the guy started insisting that we had been harassing his family but luckily, being at WDW means that there will always be witnesses around and everyone had just caught this whole scene. It was the craziest thing. Anyways, sometimes it's probably good to say something but I guess my lesson is to know that people in this world are crazy and you never know how they're going to react.