The thing i don't like is that a lot of trainers are doing it, probably in fear of thinking they'd be out of touch with the 'fitness' industry if they aren't doing what everyone else is doing. You can get around the fact that if you want to look in shape (not necessarily be a decathlon athlete) you have to do certain things. If not weight training, at least resistance training in the form of push-ups, pull-ups, etc. I mean, just look at your average gymnast.
I think most people couldn't give two fucks about overall health. If you're a woman you want to look hot as fuck and if you're a guy that isn't a baller or very famous, you'd at least want a decent looking physique. Maybe if you're in shape, have been training for a while and want to do KBs for shits and giggles than good for you. But to use them as a primary method of getting in shape is, i think, akin to going around the block to cross the street.
The thing about weights is that they are literally the body sculpting tools. You can use it to look like a twink, a mass monster, or a 'fit' looking dude. I enjoy the challenge of going into the gym and leaving everything in there and feeling like a fucking superhero.
But i'm at an age where to each its own. I'm happy with what i built. I just feel most of these people aren't gonna get the results they're looking for. Until the next fad...