Its a complicated answer. I think folks have moved from old school survival sim where death is just a likely outcome of any particular adventure, and a more narratvist take in which the PCs are main characters of a story and if they die easily its not for the betterment of the game. The middle ground is folks still want an engaging game and challenge, but the outcome of character death needs to be less common, and the player needs more control over conditions which lead to PC death. thus, monsters teeth are a little less sharp individually.
This conversation is deceptive becasue the problem isnt boss monsters being too easy, its not following the adventure day design to bring about the right challenge level. Some folks are arguing that doing the adventure day right needs to be more clear and folks need more experience in doing it. Others, want the adventure day taken out of the game and replaced with an encounters model that places challenge into each individual combat. My take has always been that you cant meet encounters and adventure day minded folks in the middle. That is the real conflict in ideals of D&D pacing. The 5E result is a really long adventure day (6-8 encounters) which doesnt match up narratively to the adventure stories a lot of folks want to tell/experience.