Robin Hanson's interesting post today distinguishes between reading that actively attempts to answer a question ("chasing") and reading that broadly looks for new questions ("searching"). I have three thoughts:
1) Let's think of chasing vs searching as a continuum. Reading further towards the chasing end has the goal of finding specific facts, while reading further towards the searching end has the goal of exposing oneself to general thought processes. Most reading modes will not fall on either end of the extreme but instead will be somewhere in between. You might have more conscious critical thoughts about the subject matter towards the chasing end of the spectrum, but whatever, conscious thinking is overrated anyways.
2) Thought processes matter, because having more ways to approach problems is useful. Exposing yourself to different thought processes can help you find ways to test for causality (e.g., dose-dependence), see different frames for thinking about the world (boosting divergent thinking), and etc. As evidence for this, Dean Simonton notes in Creativity in Science (here) that the best scientists tend to read broadly outside their particular field and maintain active correspondence with people outside their specific pursuit. Sure, this could merely be due to an openness to experience / IQ selection bias, but I'd bet there is at least some treatment effect of searching mode reading on improving cognitive style.
3) As Hanson notes, a reading mode towards the chasing end of the spectrum has advantages, as you are more likely to put down something that is impressive but not actually useful. What he underplays is that reading mode towards the searching end of the spectrum also has advantages, as it can allow you to think critically about general thought processes without getting bogged down in the details. In general, a more chasing reading mode should be more helpful in the short run, while a more searching reading mode should be more helpful in the long run. Another reason to prefer at least some searching is that without it you never would have gotten so far down in this post. And then where would you be? Screwed.