I'm actually in two minds about whether a nighttime closure would be a bad thing.
I didn't want to see the airport closing at midnight, but in reality, there is no demand for service from 1am to 5am, barring the occasional delayed flight, which could have been serviced through overtime arrangements.
If the airport was to close from 1am to 5am, it opens up potential for savings in other areas than ATC. And if those could have been passed in to airlines in the form of reduced charges, it may have proved positive.