Why do you care about having penalties attached? This is a single player game.
Whats that got to do with anything?
As a player i enjoy choice.At the same time i want those choices to mean something.If i play as a mage i want the choice of wearing heavy armour if i wish but i also want to be penalised for doing so.I just find it more interesting to spend a bit of time weighing up my options and deciding upon a course of action.If i'm free to make choices that don't really amount to anything then those choices are not really choices at all.
-----------------------
OT: If there is a quest item for a heavy armour piece designed for stealthy characters then great it should work as intended.I think it's a daft idea and a cheap way to circumvent what should be an important game mechanic but i agree it should work.