Martin Schwimmer, of the useful and amusing Trademark Blog, has withdrawn himself from BlogLines, a free web-based aggregator service. His stated grounds (not trying to imply that they're not accurate!) are that he is concerned about reframing and imposition of third-party advertising upon his materials.
This is precisely why "author choice" needs to be the principle control on reuse of material: Unforeseen problems with the context of the reuse. I choose to continue allowing BlogLines to aggregate my material. For the present. That is not because I would deny Mr Schwimmer the right to control reuse of his stuff; it is because I choose not to exercise that same control. I simply do not have the same concerns as he does, or at least not to the extent that he does. That may change; in which case, I will simply remove the Atom feed from this blawg. It's all-or-nothing for me: most of the offline aggregators are, IMNSHO, at least as prone to the problems that would cause me to withdraw from aggregation as is BlogLines.
The perceptive will notice that this same argument applies to file-sharing: That it's fine with the approval of the copyright holder, and not without that approval. The real fight is, or should be, who has that copyright and the right to approve or disapprove reuses of material, carefully avoiding the thicket of "creating derivative works from the material." See Ellison v. Robertson, 357 F.3d 1072 (9th Cir. 2004). The "free advertising" theory has been repeatedly debunked in Napster (among other decisions). Mr Schwimmer has, as his right, determined not to authorize reuses of his material by BlogLines. So I'll continue reading his useful blawg via a direct link.