headsethair,
The reason for the hydraulic switch is that it’s more common for one servo to fail than all of them at once; then it’ll be silky smooth in pitch and a gorilla in roll or something like that. Turn the hydraulics off and at least all controls act the same way in all axes!
You’d need to be a 17-stone weightlifter of the non-sensitive type not to notice your hydraulics had gone south, so a warning light would just be something else to go wrong. During the transition training for my first a/c with hydraulic controls (B206) we were told that the first step in a hydraulic failure was to slow down to recommended speed, then check the hydraulics switch, then do the CB-pulling thing. Most hydraulic problems in the 206 are caused by pilots putting clipboards etc. on the switch. This, BTW, is exactly the procedure for hydraulic failure in the R44.