So what I've been thinking about is this: if the player is faced with an obstacle (like a locked door) there should be a way to deal with it no matter what kind of character you have.

I was thinking for locked doors it would be:
Warrior: door bashing, attracts a lot of attention
Mage: magical key. Like it appears in your hand and you open the door.
Stealth: lock picking obviously.

Another example of this could be how you get around. Like when faced with a rockwall where your objective lies on the other side.
Warrior:climb up it slowish
Mage: levitate up there
Stealth: some sort of grappling hook or zipline.

So what do you guys think?

I thought of the same thing for Lock-picking, at least they could re-introduce our Open spells for mages, which also attracts attention from the light it creates

as for climbing, I would just like to see Acrobatics re-introduced for that

no need for grappling hooks, anyone can climb the wall, it's just Thieves are best if they have the skill Acrobatics up