Try playen without enchants or magic, only smith as high as potions and skill will allow and use realistic stuff like steal or iron etc..... I've tried it and the game does get harder if you limit your-self in what you do( like potion loop, wearing fortify smith to add to potions and skill etc...)
I could do all of the above,but I should'nt have to. Why not just make high lvl mobs that have resistance, high armor, lots of hp, special attacks, and so forth. These mobs could be random in certain areas or in high lvl dungeons. Look at D&D mobs, you can be a high lvl character loaded with cool stuff,but try taking on TIamat the dragon by yourself or one of the greater devils and see what happens to you.
If any of you have any of the older Monster manuals from D&D, take a hard look at some of the high lvl stuff. You will see what im talking about. Damn I wish D&D online would come out on the xbox

. I dont game anymore on my pc. I like the comfort of my couch with my 60" tv,