I get that some people want a challenge in their games, but why do you take issue when people want the 'casual' setting to be easy? Isn't that what it's there for? You will still have your hard and nightmare modes...
Personally, I was a bit worried about the no health regen after combat because I'm a very cautious player, a little OCD, and my hand-to-eye coordination has never been very good. If I survived a battle but my health was cut down to 20% and I would have to backtrack to camp (my gameplay style is kind off like a hoarder and it's only recently that I've started using health potions at all) so I'd be able to survive the next encounter. The Devs have said that one of the reasons for no health regen is that it is supposed to make us think of the adventure not just the encounter, but for me it doesn't do that. In fact, it does the opposite: it makes me obsess about the encounters and forget the adventure. Because of this I was worried, but then I thought about ME3, it had a very similar health regen with a limited set of health potions (though in the ME world you have the advantage of cover and not having to individually heal every member of the party). That made me a lot less worried.
I get that people want a challenge (I do too) but there is a difference between challenging and frustrating for me. There's a fine line between challenging and frustrating. If I die three times in a boss encounter, that's fine and I'll try again later. If I start dying too much though, it isn't challenging to me - it's just frustrating. Even if I beat the boss eventually, once I've passed that frustration level I don't feel accomplished beating it.
That's why I like the difficulty settings. It let's the player decide just how challenging they want their game to be. I'll never want to play a game on nightmare or insanity but I don't begrudge other players that level and argue that these modes should be removed (the way some people seem like they want 'casual' removed). It doesn't change my game if other people can play on ultra-super-hard settings, just like it doesn't change the game of the people playing nightmare/insanity if I play on normal. People that happen to have the skill and time to find Nightmare mode easy should be lobbying for these to be made harder, not for casual mode to be made harder.