I don't think I'll ever agree with this. I have seen this argument brought up times and times again and every time I feel that we miss the point.
Stealing money is bad, yes. Does it deserve a similar amount of time as someone who committed a murder?
Also, nowadays, people who steal money are stealing money from businesses that are protected against those very thieves (Banks, insurances, big commerces). So basically, it's better morally to steal from a bank/insurance than it is to pickpocket since pickpocketing has a direct impact on a single person.
Don't you guys have enough people in jail already?
EDIT: corrected amount of time in comparison to murder.