I thought flight information frequencies are mainly for VFR flights and not for airlines requesting WX information.
If it weren't for the charges the airlines pay for their ATC service there would be no Flight info service for VFR traffic. It's quite the other way round, it's there for the paying customers (the airlines), we're just kind enough to let everyone else use it
With the various technologies at our disposal it's used less by the airlines, but as mentioned above, if the airport has no atis or if terrain is an issue then Flight info is the easiest way of getting the job done.