yellowjkt, even assuming that your analysis is true, many companies have it where salaried status typically comes with additional benefits that hourly does not have - such as paid time off (or increased length of paid time off), 401(k), higher bonuses, etc. Those additional benefits have to be factored into your analysis, otherwise its an apples to oranges comparison.
There are good arguments being made on both sides here, and if I may just add to the discourse. At the end of the day, labor is a good, no different than a loaf of bread or a gallon of milk. I wonder how everyone would feel if the government came out with a rule saying, you know what, a gallon of milk is $15 minimum, and a loaf of bread has to be at least $8 otherwise you cannot buy it. That's essentially what this decision (and the fight for $15/hr currently undertaken by the labor unions) is saying, only with the good of human capital.
Now you might think that comparing human labor to tangible goods is silly, but at the end of the day nobody is required to have employees (scary if that ever changes) so if you put onerous mandates on employment, you will get less employment, just like putting onerous mandates on milk and bread would result in less milk and bread purchased.
In this case, employers who are faced with increased salary thresholds, increases to minimum wage, and mandated employer paid insurance, are going to start looking for other avenues (less expansion, automated workers, different industries less labor intensive). It already happened in the auto industry decades ago. The last remaining bastion is the restaurant industry - the industry most highly impacted by this. The restaurant industry is under attack because they cannot pick up and move overseas like auto did. But watch in the coming years how many restaurants start drying up or turning to robots to make our food.