Actually, the label is there because it is required by a listing agency, such as Underwriters Laboratories.
From UL's General Information Directory, Incandescent Fixtures (IEZR)
"If the requireed rating of the field wiring exceeds 60C, the fixture is marked "for supply connections use wire rated for at least ----C""
Or "If the required supply wire rating is between 60 C and 90 C, the fixture is marked with the field wire temperature rating."
The safest thing to do would be to find a light fixture that is safe to use with 60 C wire.
[This message has been edited by Tom O (edited August 07, 2003).]