I do think that things like "You deal less damage on harder difficulties" or "Bosses have less HP on easier difficulties" are band-aid fixes that don't really care about how the game is designed. Recently I've begun to think I don't really agree with the "Easy/Medium/Hard" difficulty settings a lot of games have (besides the feature some games have where it makes them very easy just so you can experience the story with no issues, I do think that's a good choice) because it's not described very well at all. If I'm playing an RPG for the first time where I have to decide what difficulty setting I want and can't change it during the game, how am I supposed to know if I'd be more comfortable playing on Easy or Hard before playing it?
Mega Man 10 was the first time I saw a game that felt like the difficulty setting actually mattered in a reasonable way. In Easy, there are extra platforms to help with difficult platforming or maybe less enemies spawning throughout the levels. In Hard, you might have to fight tougher enemies during a level or they'll have different attacks that damage you instead of just slow you down or example, and each boss will have an extra attack. It's a much more fulfilling experience than just giving the bosses an extra health bar or something.
I thought Sea of Stars was awesome with difficulty settings. You get items as you play the game that can affect a bunch of things like making items cost less at shops, letting you take less damage, but there's also ones that make the game harder in unique ways like making it so your attacks do no damage if you don't time them correctly, or reduce your HP massively but make it so blocking attacks with perfect timing deals only 1 damage. The fact you can turn each of them on or off independent of each other and whenever you like meant I was always playing at a comfortable difficulty.
There's one that just gives you 20% more XP and sometimes that's all I want. Not to make all the bosses easier but just to shorten any time I might have to spend grinding.
I also think there just seems to be a stigma around playing games on easier difficulties. If I don't want to play a game on the hardest difficulty where I do 1 damage and take 1000 damage, there will be someone out there who will say I'm "not a true gamer" and not playing the game the way it was intended to be played.