Trawling through my on-the-job-training notes from 30-odd years ago I found this gem from Harold Evans, the former editor of The Times. He was writing specifically about newspapers, but the basic idea applies equally online.
Content and design go hand in hand:
Newspaper design cannot begin to exist without news and attitudes to it; without something to express to a defined audience.
And newspaper news cannot effectively be communicated visually without newspaper design.
The problem is to communicate, within the same physical context, not one message but a series of disconnected messages, of infinitely varying significance, and to do this with speed, ease and economy in a recognisably consistent style.
Harold Evans, Newspaper Design
Update: It has to be said: the term ‘inescapable reciprocity’ is fine when discussing the finer points of newspaper design with other journalists. I’m not sure I’d allow it in a newspaper headline. And it is terrible for search engine optimisation, who would ever Google that term?