You're talking about these:
http://dlxs.lib.wayne.edu/cgi/i/imag...y=2;view=image
They were sold to IV homeowners in the early '70s as an aesthetic "historic" enhancement [[never mind the fact that Indian Village wasn't old enough to have had gas lighting originally). The big deal was that part of the price went to benefit the Indian Village Association.
When sold, buyers were told that Michigan Consolidated Gas would to maintain them forever, but after only a few years MichCon stopped servicing them, much to the dismay of the IVA. Nasty letters were written and lawsuits were threatened, but it turned out that MichCon had some sort of escape clause in the contracts. For several years thereafter a couple of old guys in the neighborhood would service them for a little extra cash. But, after many years the parts became tough to find, and so, as you note, they're pretty much non-functional now.