i dont think you can really "exploit" a single player game.
such a thing is only an issue, in any way, if it affects someone else and, as the game is single player, it simply doesn't (well not unless you are the kind of "someone" to whom playground bragging is still important...)
furthermore there are hard caps on armor damage reduction (80%) and on the limit to which you can boost gear and potions via fortify alchemy and smithing enchants (29%) which indicates that its intended to work this way because if it was not the developers would not have put a that cap into the code. the very existence of such caps represent a "line in the sand" and indicates forethought and measured consideration therefore pushing all the way up to them cannot, in any way, be considered going against the developers intent.
the "recommended" play styles suggest that Alchemy is THE crafting skill for Thiefs, Smithing is THE crafting skill for Warrors and Enchanting is THE crafting skill for Mages. if you take all three you gimp your available points under the 50 cap for class related skills and remove a great deal of the flexibility and subtlety from your character. its also no accident that you can make 100%+ smithing potions: they are to counter the fact that to build a decent Thief you shouldn't be spending all your points in "the Warrior's" smithing tree where you get +100% (or rather x2 improvements) for each armor type.
the alternative phrase for "exploit" has near always been "creative use of game mechanics" and that in truth is what is being talked about here not "exploiting"
in the end the game is single player, has flexible difficulty levels that can even be altered
mid fight, has a console that is freely assessable when it could so easily not be and full modding support that allows people to do virtually almost anything.
in short: this game is very much about how YOU play it. NOT any one else.
PS. there is ""one issue" that i can see atm and that is the Falmer Helmet and the old hat stacking bug from FO3 (new engine my backside

) that is the only thing wrong with the whole set up atm....that and
some people seem to think its an mmo or something....
PSS. 100% magical damage reduction is a much nicer "exploit" anyway
seriously my Lydia is virtually immune to dragons...