There are only a few sports that make money. Football, Men's and Women's Baskeball. That's it. So, it all comes down to how much money the school wants to put into a budget. Miami has deep pockets and can field other sports if it wants to.
Women's softball would be a "no brainer" because it's a very popular sport in the US. However, besides money, I think the biggest issue is land. Land is very precious around campus. I don't think the administration wants to give up any land to build a softball stadium.
There are no other men's sports because of Title IX which states you have to spend equal amounts of scholarship money on each gender sport. So, if Miami added another Women's sport, they could add another for the guys.