A $15 minimum wage would also makea lot of small, and even some decent sized businesses loose a lot of money, or go out of business really fast. Yes, low class people may have more money, but jobs would also start disappearing, leaving more people unemployed. The direct advantages are good, but long term th economy and low class would end up suffering.
Anyways, the point of mininum wage was to give people a starting point. People are supposed to use these jobs to allow themselves to climb corporate ladders and be successful. They weren't meant for people to live off of, especially not families.People want to be able to do minimum work, and do well, but life doesn't work that way.