Length is no substitute for substance. However, reality, as they say, has an surprising amount of detail. That means if someones goal is to adequately represent it you will not be able to do so in a engaging, polemic one-liner that puts everything neatly into a box.

Note that within my argument the arrow of causality points in one direction: To explain complex topics adequately a certain amount of length is needed. That obviously doesn't mean long texts are automatically the more adequate explaination of a complex topic in all cases.