Seriously? You're argument against decriminalized pot is the extra money spent figuring out the legal details? The amounts spent is a thimble-full in the vast oceans of money we're already spending on this useless prohibition part 2, aka the War on Drugs, in law enforcement personnel, equipment, time, courts, lawyers, jails, lost jobs and productivity and on and on and on. The solution to your money problem is for the feds to also decriminalize it, let states and local jurisdictions decide if they want pot legal in their communities, then spens their own monies either regulating it or combatting it.
If enough states decriminalize it, the feds will have to follow suite, as it will be obvious public opinion is against them.