1) Vending machines should bring their product to us as robotic dispensers which solicit their tasty fare directly to the consumer. In North Korea, the machines would poke you with sticks until you purchase something.
2) A large crank could be attached to generate electricity for purchase by local power companies. Once the customer has produced enough electricity to buy the product, a selection can be made. This would help the environment while burning calories.
3) Scales could be placed in front of vending machines. If a hungry patron selects any unacceptable junk-food item, a loudspeaker at the top of the machine will announce the weight of the individual and the product selected. Embarrassment tactics promote a healthier lifestyle.
4) Vending machines should fight to the death as huge mechanical warriors. We would have the benefit of a new sporting event while improving on each generation of machine through "survival of the fittest". Convicted felons and individuals with unpaid parking tickets could be forced to purchase items while machines are in battle.
5) As we all learned in “Maximum Overdrive”, vending machines can defend themselves by shooting out cans of soda at high velocity. Therefore vending machines make ideal baby-sitters. It can protect your kids, and if you fill it up with nutritious snacks you'll recoup all the money you spent in diapers by charging a nominal fee. Warn the kids not to anger the vending machine.