It's way too easy in my opinion, but as you noted dials exist and I have used them to up the challenge level.
Classic D&D was way too hard, so much so that everyone I ever played it with over 40+ years house-ruled the stuffing out of it to make it a little (or a lot) more forgiving.
@LordEntrails may be right that if you have to err to one side or the other, it's better for the popularity of the game if it errs on the "too easy" side.
For my preferences, it's part of a much broader nest of changes that have shifted
so much of "what the campaign is about" to the very beginning, before play has even begun. The campaign is going to be about
these Big Damn Heroes (even if they're just 1st level right now), and they're big damn heroes so they're going to need heroic ability scores and lots of background options and special powers, but now character creation is slow af so we better make them hard to kill, and we're gonna need a story for them to be the big damn heroes of, can't just have them robbing tombs for treasure or exploring wildlands for funsies, and on and on. And since we have to work all this out ahead of time, we gotta have a Session 0 where we talk about what the game is going to be about before we play it, because otherwise we won't know what sort of Big Damn Heroes to optimize 1-20 before we start playing, and...
Am I ranting? I really like the 5e rules. I think the design itself is indeed 40 years better than Classic D&D. And I should say that I contributed to the evolution of the game over the years, because my friends and I were trying to play Big Damn Heroes with AD&D back in the early 80s. I think the publishers have largely been trying to give the people what they want over the years, with mixed success. But I still miss the kind of play experience you get when you roll up an adventurer with a one-sentence background in five minutes and go find out what's in the big hole in the ground at the base of the pyramid. Maybe what you discover will lead you to becoming a big damn hero, or maybe you'll be rolling a new adventurer in half an hour, but genuinely not knowing what's going to happen is freaking magic.
5e, as designed, kinda stinks for that.