For example, a soda machine sells drinks for $1.25 USD. Currently, this is approximately 0.021 BTC. If/when BTC hits $126 USD, the price will be 0.00992. 5 decimal places just to represent the cost of a soda. Or 9.92mBTC, which is arguably much more user-friendly.
It's up to the soda machine owner to make this decision. It's literally not our business.