You know, if you are a dedicated sneak character, your inventory is pretty low.
You have a light armor and not many equipement... An not much additionnal charge.
It means that when your sneaking time is over, you end up weaker than the other characters. If you want to survive, your only option is to hide, then run to base to get additionnal charge. (being unsneaked during all the way back)
If the character get stuck, you have no options at all.
Plus, even the environement can kill you then.
The problem was never that the sneak lacked penalties. They have a lot of them.
The problem was the lack of balance in their offensive capacities. Which was reduced, apparently.