Safe use of public parks is a great thing to encourage. We should also try not to waste the City's limited money (which is really our money) and we should try reduce our use of electricity because for the benefit of our environment.
Instead of "either or" thinking, there are ways that we could have both. Maybe motion sensors could be installed so the lights would come on (and stay on) automatically when there is someone there to use them. Or, like Raymore, Missouri, there could be a "user activated system" that lets people push a button to turn the lights on for a certain amount of time.