One liners are an (extreme!) optimisation and programmers feel quite proud when they able to optimise code :)

And it's not restricted to Perl: http://news.ycombinator.com/item?id=4906370

> Then again i've seen a lot broken, half-tested and unmaintained CPAN modules as well.

You also get this in PyPi, Gems, NPM, etc. Just more proof that Sturgeon's Law exists.