Apparently, to summarize several responses, brevity is key. Well, I like brevity as much as the next person, but I also like explanations and arguments, and it seems that most quotes achieve conciseness at the cost of leaving out the "why". So after reading a quote, I can have one of three responses:

1. nod my head in agreement if it's something I already knew
2. track down the original book/article to find the explanation or argument
3. just move on with some amount of frustration

1 and 3 don't provide me with much benefit, and I usually don't bother to do 2, because of the hassle involved, and because I don't know whether the source material even contains an attempt to argue or explain.