More specifically, he said there were two reasons against understandable writing:
1) Scientists are lazy, and do not want to read long passages. Coupled with the fact that they are usually pretty smart, they can understand the terse language.
2) Scientific (read: incomprehensible) writing removes all biases. There is no room to interpret something incorrectly if the precise words are used.
I agree though, it's not a very inviting culture that promotes these ideals.