On the other hand, blogs risk making everyone dilettantes, switching from one thing to another without ever thinking deeply on it. Many topics simply can't be condensed without losing key points. (I will ignore the further issue that many blogs are completely vacuous, on the basis that we can all choose to ignore those).
Not that there is a problem with being a dabbler in lots of different topics, as long as there is deep thinking about some things! My answer is to try and write in length when a topic needs length, even at the risk (or likelihood) of making my writing less popular – most of my articles are 1000 or more words long. If you don’t think in word length – this entry including this sentence is 173 words.
(As Wittgenstein said at the beginning of one of his talks, commenting on what was possible to condense into a single discussion: “Another alternative would have been to give you what’s called a popular-scientific lecture, that is a lecture intended to make you believe that you understand a thing which actually you don’t understand").