Stealth... honestly, I kind of hope it disappears entirely or becomes something (semi-)magical. It's ridiculous otherwise from a realism standpoint. From a gameplay standpoint, unless the whole game focuses around it (like Metal Gear Solid or something), I think it makes more people angry with either it's limitations or overpoweredness than it makes happy. Personally, I don't understand the appeal of walking past half the game anyways. Unless the stealth system (really the movement and NPC detection systems) is intricate enough to be require skill from the player (not the character) it just seems boring to me. I know it's not going to happen; stealth will definitely be in the game because we all know that a character is either a fighter, a mage, or a thief and Bioware won't alienate 1/3 of the RPG players out there.

But I can dream.
No ugly mage hats. I kind of like systems where you choose the look of your armor all the time and just find add ons to upgrade the stats. Maybe you can unlock new looks too, but they shouldn't effect the stats. On the other hand, it's kind of a game breaker. ME2 kind of did this, and it kind of worked with the sci-fi backdrop, but it would probably be too cheesy in DA2. Regardless, those hats were dumb.
I'd also like a camp with people doing useful things. Sparring, gathering firewood, cooking... even fun things occasionally like gambling, singing, or playing fetch with the dog.
And as for insanely flashy bright spell effects... Well, they should definitely at least have the visuals disabled in cut scenes. I'd prefer them to have the visuals disable entirely, actually. Especially for non-magical abilities. Maybe glow for a second and fade. But unless the spell description specifically says "Grants you a bonus to defense by conjuring a mass of glowing, swirling particles that distract the enemy but (due to the extreme magicality of the magic), doesn't bother the character or his companions when the lights float 2 inches from their eyeballs", there should be no mass of glowing particles. Even from a gameplay perspective they're annoying; it's much easier to see what effects are active by looking at the icons by your health bar.