I have a hard time imagining lighted turn indicators being very effective.
-Drivers don't expect them. It's a mistake to rely on drivers being able to figure things out. And they tend to get testy when you surprise them.
-They're going to be too close together to be easily distinguished from a distance or at night.
-How can you be sure it's really on or that you remembered to turn it off?
-Hand signals are far more highly visible and versatile. I use my combination "turning left (arm extended)... yes, YOU (pointing directly at the driver I'm about to turn in front of)... I want you to stop and wait while I turn (palm of hand facing out)... that's it, thank you very much (saluting as I go by)" all the time.
Try doing THAT with a blinking light!
RichC