It's all about understanding the medium. The Economist makes a wide-ranging, newsstand magazine that isn't too far different of a medium than like a weekend Financial Times paper. I think blogs, or free-ish or frequently publishing substances, naturally slot into that kind of medium where you want to pack the most info and analysis into a deftly concise format.

If you want to write long form, please use a medium where that is naturally part of that medium. Quarterly magazines, books, full length investigative pieces, etc. An important part of WHY longer form writing works in those media is that the author is understood and expected to have devoted much more time and work into it, and doesn't output content so frequently. In other words, respect the axiom that the medium is also the message.