The proposed building for the 2nd district doesn't include a social hall.But back to my original thought, why do taxpayers pay to have reception halls?
One reason for the hall is that rentals (and bingo or poker) contribute to the finances of the company and reduce the reliance on tax funding.
Apart from the primary emergency services function of the station, the hall is probably one of the main community benefits of a fire station. Outlying stations in career departments are often a small two-bay structure with minimal living quarters for the crew. No community benefit beyond the fact that it happens to house an engine and ambulance to respond to calls.