Это было осознано еще в 1984 году:
> -- Цитата:
> "When developing or reusing software components, one is often forced to study sourcecode.  In  many  cases  this  code  contains  only  little  or  even  no  design  information,which makes it hard to read and understand it. This is the main reason, why softwaremaintenance  costs  dominate  over  all  other  life-cycle  costs.  Standish  (1984),  forexample, discovered, that the time needed to understand source code, causes 50 to 90percent of the maintenance costs. Therefore high software quality, in form of readablesource code, is the best way to save time and money for new developments."
http://www.literateprogramming.com/rlp.pdf

К сожалению, сам первоисточник
Standish, T.A. 1984. An Essay on Software Reuse
не смог найти.