Hell, TeX version numbers are just additional digits of pi (latest version is 3.14159265), and Slackware jumped version numbers from 4 to 7 because people kept thinking it lagged behind Debian's whole-number versioning (ultimately, Slackware's version numbers would have surpassed Debian's even without the artificial bump, but whatever). Arbitrary indeed.
As a mathematician, I prefer the expression "converging towards perfection" :-)
More seriously, might be a urban legend, but I was once told that upon Knuth's death, the TeX code will be frozen and all remaining bugs will be permanently declared 'features'.
