Stop crying, you say that you want to specialize as a mage but start crying when you see something that your mage cant do, it is like calling a hairdresser to do a high precision coupling alignment on a steam turbine, unless he has skills outside of hairdressing odds are he wont be able to do it. Picking locks and pockets, disarming traps and slipping by the enemy undetected are what define the Theif skill set, if you start allowing mages to do everything the theif can do but better then why bother with the Theif skill set at all? If you want to play a pure mage then fine however dont expect your character to be able to do everything that the other archtypes can do but better, and unless you join the Theives Guild (which if you are a pure mage you wont do) you will not be forced into situations that you cant resolve, if you are talking about not being able to access the loot of a locked chest however such is the price you pay for having such a strict stance on character archtypes.
That being said I dont see how having a mage or warrior learn how to pick locks breaks character, there are plenty of reasons why these characters would learn how to pick a lock however if you imagination is limited to creating characters that can only stick to skills that relate to their current archtype then that is your problem.
When my mage could do it previously? Without needing to get hamstrung into Stealth skills?
I care because a choice I had previously is gone. I could pick the lock or magic the lock open. Now I can only pick the lock. Pardon me for getting aggravated when a series that is
supposed to be about character freedom tells me I can only do things a certain very specific way. Leave the telling in my quest journal. How I accomplish my objectives is my business, and I don't want the game trying to throw a wrench into the way I want to play.
If I had it my way, every archetype would have its own means to bypass locks: warriors would have lock-bashing, mages would have unlocking spells, and rogues would have lockpicks. This way, this little problem would never come up, because every character would be able to find a suitable means to bypass the lock. Simple to implement, and makes everyone happy.
That is my stand, and my thoughts. Yours obviously do not follow mine, so we have nothing more to discuss.