I recently spoke with someone who helped write some of those exceptions and he said that they were a result of lobbying, including his lobbying, not that legislators added them for fear of having the statute thrown out by the courts.
> I can't actually find the thing I am looking for. AFAIR the Cornell law site does not have the updated version that I need to reference, but you can see by the exemptions granted they are just codifying your rights to continue to use a work, even if it is not necessarily obsolete, if the copy protection has gotten in your way.
The exemptions are issued by the Library of Congress and don't become part of the statutory text.
It's true that user advocates have argued that fair use is required by the first amendment and cited some text in Eldred for that proposition, and it's true that proponents of the DMCA have argued that fair use is accommodated by the exceptions and exemptions. Still, proponents of the DMCA have never admitted that the DMCA would be unconstitutional without those exceptions, nor that the DMCA is unconstitutional if those exceptions don't work or don't protect users' rights adequately.