(...) Make it so crouching is not a sufficient means of sneaking (...)
I don't agree. All I say always keeping in mind that I talk when using Sneaking with the appropiate character, not with a full armor warrior just because it's cool to have the skill and perks.
I agree that it's not very realistic to be able to sneak on day light, but if someone decides to play a sneak character (rogue / thief / assassin), will need all the advantages that lacks from a normal warrior (melee damage / armor). Unless we are able to shoot some kind of "water arrow" that turns torches off, to be able to sneak (let's say it was some kind of perk for sneaking skill), then you can't force the player to always have shadows around, or else the skill training + perks are completely nonsense. And also, having no light would mean that anyone is able to sneak, so no need of sneaking skill either.
Sneaking on this game is some kind of "hiding" skill, so you can think on this as someone that is able to hide himself next to a wall, while walking, even if a light is around. Something that a mage or armored warrior should not be able to do (when talking about RPing).
With my rogue I'm enjoying the sneaking, and I have also fun training it slowly, while playing (not force-training) so for now I'm not either overpowered, neither still good enough at it, so I have to be really careful when sneaking. Of course when I train it more and have more perks, it will be easier and I will feel more powerfull, which will be also cool, because it's hard earned, and it's what I was looking for. But when I start the game again with a warrior, the sneaking skill will be a no-no, meaning I will never use it.