Because it's non-negligible source of warming greenhouse gases that is completely avoidable - we have plenty of substitutes available to us with lower global warming potential. Releasing 1 kg of CFC-13 will trap the same amount of heat as 14,000 kg of CO2.
Project Drawdown lists managing refrigerants as one of the top 10 solutions to limit warming in both 1.5 and 2C scenarios.