Yes, but I can even do that now, yet I almost never use it - maybe at race start if I don't want to pit but let the field through. During a race in LFS it can even be dangerous sometimes, because different people have different intentions with the indicators. One group (me included) indicates to the left saying that they will move to the left to let the others pass. For the other group indicating to the left means the opposite: "pass me on the left!". The result when these groups mix is not nice.
Reading the original post again, I seem to have missed the auto turn-on, which I'm of course against. Auto turn-off should be implemented for cars that have it IRL too, not because it has a ground breaking effect on racing, but because it's those little things and details that make a game so much nicer.