I don't, mostly because I don't care how other people play their games.
The only thing I can tell you is that its not useless, as you assumed only because you and most people don't use it
The only "useless" perk in it is the "unbreakable" for the reason you stated, you find too many lockpicks, all the others are somehow useful, both for role playing a thief and for a regular play
about useless perks then what you think about the head cutting one? that triggers the head cut animation when you kill someone who was gonna die anyway, tell me how useful is that?
Not to get off-topic but because you asked, according to the talent description, it adds 25% bonus damage in addition to decapitation. So technically it is more useful than all of the lock picking talent tree.
Yes I agree with OP.
The lock-picking skill is rendered useless once you master the lock-pick mini game! If they wanted lock-picking to be unique and useful as a skill it should have worked as a % chance to open based on your skill level and talent allocation. Compare it to blacksmithing. I can not smith dragon armor without the Dragon Armor Talent. Even with 100 smithing I can only craft a few things if I have no talents allocated to smithing.
The game at times shows serious inconsistency, evident in the talent tree especially.
The OP is right, mages used to have open lock spells, they worked fine because they required appropriate levels of alteration skill to open equal level chests. Why this was removed is beyond me.
If it's not broken, don't fix it.