"Perhaps the practice of taking code for granted has come from a history full of languages where code isn't formatted in a personalizable enough way for its purpose to be clear."
Yep. There's more pressure to take code for granted in languages so verbose that everything is non-trivial to read. It seems to have been a slippery slope from having such languages to assuming take-for-granted-ability was an unabashed virtue.
That is perhaps the biggest disadvantage of C and relatives: they kept programmers from bulking up on their reading muscles, the ability to read concise code patterns at a glance. Perhaps this is partly what Dijkstra was referring to as 'brain damage'. (http://www.cs.utexas.edu/~EWD/transcriptions/EWD04xx/EWD498....)  Fortunately it is curable, no matter what he said.
 What I was referring to as static languages, where functions can't be redefined dynamically.