Well......I guess I'm not that worried about it. I'm thinking it's designed as insurance that it won't short against a glare shield, etc. More importantly, I had access to a couple of HID bulbs so I tested it out.
I took a damaged D1R and stripped all the insulation from the return wire by carefully crushing it with a pair of needle nose pliers. Plugged it in and it did a quick "Click-click-click-click" but did not start. Damn, I just realized I should have checked to see if the bulb worked to begin with. The base is cracked all the way around, so I don't know if it's that or the stripped insulation which is the culprit.
OK. I take a used D2R and check to see that it does work. I then remove the top centimeter plug it in....KABOOOOM!!!!
Seriously though, the bulb lit, no problems whatsoever. I then crushed the next centimeter and it still worked fine. I finally crushed it all the way down to the base. I didn't want to leave the wire exposed with the base metal mount adjacent so I left the last centimeter that is in the base. Still worked fine.
Some crude calculations:
The wire is about 8.5 mm from the center of the bulb. The return wire is les than 0.5 mm thick. The Ceramic insulation is at least 2 mm thick. If we model the lamp as a point source radiating with a infinitely long return wire, the insulation blocks 2/(2*3.14159*8)% of the light while the bare wire blocks 0.5/(2*3.14159*8)%.
Doing the math, the insulation blocks 4% while the wire blocks 1% so removing the insulation will give you a hair over 3% more light. In addition, that shadow is just plain ugly.
What's next? I'm going to try a D1 style bulb. I will have to find something that is nonconductive and highly heat resistant to keep the last bit of insulation in the base (Plumbers Putty?) I don't want the thing to slide to the tip of the wire and have a vibration or problem cause a short.....