As a regular urban cyclist, I don't know if it's a good idea.
1. An oblivious driver is probably looking at head-height or above, likely not at the road itself.
2. If they do see a wobbly green light, it's one more thing to distract them.
I follow the road rules very carefully, so I can be "holier than thou" to all the idiots on the road. And from what i've seen cyclists, drivers, and pedestrians are usually at fault in equal percentages.
The biases from both drivers and cyclists are incredibly one-sided. I nearly died in a cycling accident about 4 years ago - every single person asked me what the car was doing wrong. In all honesty there wasn't one, it was just me and a streetcar track.