That's all Hero Mode is? I hope there's more to it than that. Turning off heart spawns and doubling damage sounds like an incredibly simple thing to add, that just required a bit of testing to make sure it was feasible.
Maybe there'll be a surprise to it, like halfway through, or once you get the magic armor (I forgot WW had magic armor), where it suddenly says: "Guess what? The Double Damage has been DOUBLED!"
Honestly, though, tweaking damage output and cutting down health regeneration spawns is a classic "lazy videogames" way of adding difficulty. I hope we find out they made the dungeon layouts more challenging, mixed up the placement of items, or something.