D&D in the WotC era (and arguably in the late 2E era) has moved away from "boy, I hope I can survive sneaking into this sewer and stealing a few coppers from under the nose of the wererat beggar king," and rolling up a new character in a matter of seconds when it doesn't work out.
Modern D&D -- and fantasy more generally -- has shifted toward a more character-centric view, where players and audience members can generally rely on a character they're introduced to eventually becoming incredibly powerful and a master of their world (or plane). The challenges they face are generally not ones that threaten their lives, but their values or other goals. 5E helped create and now follows this trend. It also means that more cozy game play (popular in fantasy fiction and media nowadays) is also more doable than it was in the old school era, when PCs didn't really expect to live long enough to open a bookstore, or whatever.
5E also appeals to the more mechanically inclined folks who were onboarded with 3E and 4E (although a bunch of them also branched off to Pathfinder), who like the more detailed tactical and especially character-building options.
I think both old school and 5E-style games have their place, but they're each better at different things.
If I want a gritty dungeon crawler or horror game, I'll go with an OSR system, where characters are almost certainly weaker than all their foes, have fewer tools in their toolbox than their 5E counterparts and running away is always a good idea.
If I want to tell a story about characters solving problems, especially heroically, and growing as people over time, I don't want to use an OSR system where they're likely to be cut down, midway through their arc, but instead prefer a system like 5E. (Daggerheart also seems like it's aimed at this audience.)
The problem is that the Dungeons & Dragons brand has, at various times, embraced/originated both styles, so there's a mismatch of expectations. A 1E D&D adventure just works differently under the 5E ruleset and vice-versa, although people can and do make it work to their satisfaction.
Neither style of play is wrong -- I run multiple 5E campaigns as well as an ongoing Shadowdark campaign -- but they're serving different audiences looking for different things.