I am at Level 57 I have completed all the major quest lines and have become very powerful indeed. For me, the game was excellent, and the strugglle to get to this point has been thoroughly enjoyable. I haven't got much left to do and nothing seems to present much of a challenge anymore. Fine ! I call this, nearing the end of the game. I still potter around looking for smaller quests and looking fpr peerless items (haven't got them all) But the major part of the game, The "Getting here" is done. It's probably time to move on.

I certainly can't complain about being OP though. That's what I have been trying to achieve all along, after all !

Now that is the attitude to have.

You can become OP if you want, that's what going up levels is for after all. Myself, level 55, no armour, no impact, only two reduce cost enchantments each on destruction and restoration, overdid the smithing only to keep using the Ghostblade a viable option, and only on expert, I still find my fortify destruction and fortify health potions are my character's best friends, still finding some enemies a challenge (though to be honest, they fall into either 'kill you with one or two hits', or 'are they joking, daft enough to attack me, is it?')

Self-gimping is pretty much required for any build in this game. I gimped my sneakless archer by only using a long bow (upgraded through smithing), iron arrows, and hide armor. I also don't take the Ranger or Quick Shot perks. Suddenly, the game is fun again.

I feel that this is a problem with this but with you I think you should at least raise it to master before you say anything. I think it's odd you'd even say anything until you at least tried master. If then you still have the issue then downgrade what you have or don't use everything you have acquired.

Try this build:

Pure mage, no weapons allowed.
May not wear armour or any form of enchanted apparel.
May not take any magic-related perk.

Lol 1 spell cast - out of mana.

As a level 37 thief, I've never felt it was too easy. But, then again I resist the urge to perk the things that seem unrealistic like that. There are plenty of opportunities to make your character basically unstoppable, I just see them and recognize that my character is not and should not be unstoppable. As a thief (and not an assassin) it's important (IMO) to not be all that great as a warrior. But this is basically just me putting limits on my play. And so that may not be for everyone. Frankly, if I played as a mage I would want to be unstoppable in the way described in the original post. That is why I would learn magic in the first place. A simple draugr should be no match for a skilled mage. A dragon priest would be more difficult but still it should only be a matter of time. If a mage is skilled enough I see no reason to not be unstoppable.

But I do agree about the insanely difficult bosses. I love games that put in tough bosses that you don't necessarily "have" to fight but if you do, and you come out alive, the rewards are massive.