We can't all be the same I guess.
The only thing I take slight issue is with what you say here...
Finally, maybe I'm a prude but I don't recall so much crude language in the 1st 2 seasons. These kids are what 8th-9th graders? Was using the F word in every other sentence for effect? It just seemed forced to me. Are young kids watching this series? I hope not. Guess shows aren't rated on paid services.
The F word was only used once in the entire season and yes that was the first usage of it in the series. It was implied on 2 other occasions but never fully said or heard so I do think you are being disingenuous a bit here with the 'every other sentence' remark.
The swearing did come into the the show in season 2 and caused quite a stir at the time but I don't feel the levels of it in 2 or 3 were overtly inappropriate. But that is me, I do understand others feel different about it.
It should also be said that the show has a PG-13 rating in the US and the level of profanity, violence, gore used in the show fully sits within the regulated guidelines.
In the UK and Australia guidelines are stricter and the show is rated 15+ so between the US rating guide and those elsewhere you get a good enough idea of just how appropriate it is for young viewers. IE it's not appropriate for pre-teen kids and parents are fully warned beforehand by the ratings given.
I wouldn't let my kids watch it, but they are too young. It's not a show for young kids at all.