Pickpocketing is actual too useful thus it break the games.
1. Steal from majority of stores thus allowing unlimited funding. This reduce difficulty (free rod of resurrection charge allow for all kind of battle healing...)
1a. Steal from store to reduce their stock thus raising the buying price. Example: a store has 1 item of the type will buy at 25% itemprice, but with no stock will ask for 30% itemprice, the basic buying threshold of all store. This is useful if you play with max Bayle/Cowled Wizard fee and thus have huge need for gold.
2. Steal from certain NPC thus reduce their tools to be used. Example, cursed sword of berserking user cant do his best without that sword after we cast remove curse on him and steal it. Or taking potions away from the guards so they are without healing tools in the coming battle.
PP is a valid investment, comparable to detect illusion/traps.
What I object to is the relative easy threshold to steal in store. Only Bernard in Copper Coronet has a somewhat realistic threshold for shoplifting. Once you raise the shoplifting to 150+ that would limit the shenanigans. Raise it to 200 and you have a healthy playstyle.