Paul O'Leary, Elisa Walker, and Emily Roessel of Social Security's Office of Retirement and Disability Policy have written an article titled Social Security Disability Insurance at Age 60: Does It Still Reflect Congress' Original Intent? I won't hold you in suspense. Their answer is "Yes."
Having looked at the legislative history of Disability Insurance Benefits, I'd have to say that it's impossible to answer the question. The program now is dramatically different than when it started but those differences have to do with amendments to the Social Security Act rather than anything to do with its administration. Sixty years ago there weren't even any cash benefits, for goodness sake! Of course, it's changed.