Given the substantial discounts operators get on published parking charges, rebates, etc I suspect passengers pay for parking their cars is much more profitable than airlines parking their aircraft!
I imagine you are right, and when traffic was well down for 4 or 5 years it was probably a very good move. The irony in a way is that 5 stands were returned for a/c parking for the winter, but presumably it's because there is less demand for car parking at that time of year. What is perhaps more surprising is that in summer, when there are much more aircraft movements (with less a/c just parked up) and more passengers, with the extra revenue they both produce for the airport, it is the increased demand for car parking that gets priority.
That said, nobody has yet confirmed that the 5 stands are definitely reverting to car parking this summer, and with traffic continuing to grow surely there must come a point when more stands are justified, not 12 less than what we had 10 years ago.