[ivanr]

Because "everybody uses RC4" (the sibling comment from dchest is correct). There was a lot of bad cryptography in that period and not a lot of desire to improve. The cleanup only really started in 2010 or thereabouts. For RC4 specifically, its was this research paper: https://www.usenix.org/system/files/conference/usenixsecurit... released in 2013.