I found an interesting article on NPR and it’s something I’ve noticed also. More and more male singers are sounding like women. Back in the 80’s you had hair bands with guys wearing makeup trying to look like women. These days it’s men with falsetto voices making it on the radio.
Adam Levine strikes me as one of the biggest male perpetrators of lady tones but he’s certainly not alone. These days in the music industry if one style is successful you’ll see clones for years until the next “new” thing comes along. But there have always been guys singing high. For a obscure example I’ll go with Mickey Thomas with Starship. Prince could hit some high notes, his song Kiss comes to mind. Then, of course, there were the Bee Gees. Maybe it’s the lack of variety on the radio these days that makes it seem like such a majority of male singers only sing high.