This functionality would be highly useful for mobile applications. Often one travels and connects to a guest wifi. Then returning home you want to reconnect to your home-base wifi automatically, and without having to reenter the SSID / Password.
Sometimes one wifi network can go down but another is available. Consider a 2 wifi networks from the same source, but 2.4 ghz and 5 ghz. It would be useful to connect to that secondary network automatically while reserving cellular connection as a tertiary backup. Some users just want the function without having to learn how to program and compile.