The volume is controllable. and the information about what your aircraft is doing aerodynamically is incredibly informative. It saves me from putting my eyeballs in the cockpit (to check airspeed), for numerous other reasons... Without looking at any other instruments, I can tell, just from the sound in my headset if I'm operating the aircraft at optimum aerodynamic AOA for glides, climbs, and most critically, for approaches. And if I'm not, I can immediately and easily adjust my back pressure (the AOA), (without focusing on any cockpit instrument), and get instant aural feedback.
How many times do you look at the airspeed indicator? Without even touching on the fact that for almost everything we use the airspeed for, it's actually the AOA that's really the critical important parameter, imagine not having to do that, being able to keep your eyeballs on what's happening outside the aircraft, instead of what's going on on your instrument panel.
In the General Aviation community, unfortunately, we have established and propagated the idea that the only thing AOA is useful for is to let you know when you have stalled the aircraft. That was, and is a mistake. AOA is the primary aerodynamic parameter for everything affecting how the aircraft performs.