Yes they come on in the locked position (headlights do not) so does that make them Parking lights only? I never leave mine set in that position, wouldn't really know why I would. Well I guess if I was broke down on the side of the road...
I lived in Germany for several years; the Germans have some streets where you are required to park with your lights on. With the engine off and the key out of the ignition German cars give the headlights just enough electricity to light up without killing the battery too fast. Motorcycles have much smaller batteries (obviously), so even that trickle of electricity would yield a dead battery fairly soon. It's not so difficult to find a hill to roll start your bike, but it is inconvenient. The manufacturers put low power parking lights on the bikes so the battery will last longer. Alternatively you could just park somewhere else.
As to why you're required to keep your lights on on those streets, I have no idea, but I suspect Germany isn't the only country with such requirements.
I think that requirement to leave the lights on on parked vehicles really takes on new meaning during Octoberfest. Think of all the Liederhosen that have been soiled when drunks ride up one way streets the wrong way. If they see the lights, they may not venture up the dimly lit road in question.
It saves the municipality from having to install street lights and it keeps Liederhosen fresh.
I can attest that the lights will not kill the battery if left on accidentally for 9 hours, because I did this twice when I've parked at work in the morning and find the lights on when I get off in the afternoon. I was impressed.
I would think you would want other drivers to know whether you plan on turning or not. If you get rid of the external signals and use some obscure little light buried within the headlight housing, you could be putting yourself in danger.