I agree that curation rewards for comments should remain.

Regarding the segregation of content types, I think it could make sense to separate reward streams for top-level posts versus comments since there is a distinction made between the two at the blockchain level (the payout times for comments is entirely driven by the payout time for the root post). So this blockchain difference means that comments (posts with depth level greater than 0) should really just be used as commentary on top-level posts rather than other purposes, and so their visibility is expected to be very different than top-level posts that it can perhaps justify a segregated reward stream. (By the way, this proposed hard fork is a good time to finally get rid of the 4 post limit on full payouts. Then posts can be used for microblogging without limitations, and we don't need hacks like using comments on unrelated root posts for microblogs.) 

But like you, I don't really like further hard-coded segregation of content types, such as the one between "original content" posts and "link" posts. I think those should just come from the same reward stream. However, I do see value in different types of content having a different percentage of the payout allocated to the post going to author rewards versus curation rewards. People are willing to reward the author of original content more than just a shared link. In fact, in the case of the shared link, the author of the post is really more like just another curator, so perhaps what would be ideal is to distribute all (or nearly all) of the payout to the curators for shared link posts (and the author would of course be the first curator). For original content, the author deserves a large fraction of the payout, but they should still give some fraction of it to curators to keep sufficient motivation for curators to upvote the post in the first place.

So, I suggest that the only segregation of reward streams be between posts versus comments, but to furthermore allow the author of a post/comment to specify the percentage of the payout that goes to the author (with a hardcoded maximum allowable percentage of say 80%) and the rest going to the curators. This percentage would be visible on the post so that it can inform the decision making of curators. And once again, get rid of the 4 post limit.