I wrote a blog about this yesterday: https://steemit.com/steemit/@daut44/steemit-needs-to-change-its-reward-system-to-better-incentivize-intelligent-discourse-in-blogs
Essentially, just as you state, I believe the comment section of posts should be full of intelligent discourse and a disproportionate portion of rewards go to low content blog posts. The comments should be the lifeblood of the site, not empty praise. And the only way to cultivate that atmosphere is to reduce the opportunity cost of writing insightful comments in blogs that arent your own. Sure some people will do it for the pursuit of truth, but most need incentive.