As a person with several transgender friends, I am aware that (while they would not make a big stink about it or act like, as some might say, 'snowflakes',) they would probably be happy with the phasing out of "guys." Probably doesn't go over well with women that aren't used to being called "guys" either. Obviously it's a term that's not meant to be mean, but also it's not gonna kill anyone at WDW to see the death of the word "guys" - my thought is that if it takes like .2% effort on my part and makes someone else's day 100% better, then like, why not switch?
I know that even before the "5th Key", there was a strong push at Disney to not use "guys", with training to use themed dialogue, or else in an unthemed area to say "folks" (as in Mickey's "Hiya, folks!"). Of course, like how not every cast member is always "in theme", neither did everyone stop saying "guys." In other words, this is not something new, but probably something that is being pushed now more with the new key.
I do agree though, Friends sounds fake, and I hate it when people call me that - you're right, I'm not their 'friend'. I also agree that "HI FRIENDS" sounds like "HOWDY SUCKER HAVE A *MAAAAGICAL DAY*" I PERSONALLY would prefer to be called "guy", but then again I am a guy. Using terms like "Hello, everyone!" or "Hey there, Explorers!" seems better. When I worked there I would say "Hey there, movie stars!" and "Namaste, travelers!" Easier for everyone, fun for the kids, helps immersion, and when you get the words in your mouth and with repetition it begins to come out of your mouth more easily.