Well, this is the first ES game that I've played, so I had no idea it would be like this, but seriously how hard would it be to indulge hardcoe gamers like myself and just add another difficulty level where opponents hit way harder, have a lot more HP, and are better at sneak detection?
Every TES game, from Arena to Skyrim, is designed in such a way that you can be as strong or as weak as you want. It's one of the many things I enjoy about the series. I can "cheat" without cheating. If I wanted to jump across the map in Morrowind, I could do that with a buttload of gold and some insanely powerful "fortify Acrobatics" enchantment. If I want to one shot a dragon in Skyrim, I can max out smithing and enchanting and make a pair of weapons even the Divines would be envious of.
However, no game ever has added more difficulty to it's Stealth system; even in games where it could be done by simply changing some numbers around like this one. Sneaking is based on the amount of light touching your character, the speed you move, the weight of your armor, and the sound you make while being checked against your skill level. Increasing the difficulty will increase the enemy's damage and resistances, but not their ability to detect a sneaking character, for some reason. Even in older RPGs, like Fallout 1 & 2 or Planescape: Torment didn't increase the difficulty of sneaking and, like with all games, Stealth was "OP" in those games as well at a decent level.