I concur with some of the above that there is no ethical problem with your downloading more content than you believe you can read.
If the author releases it for free as a promotional tactic, they have to understand that some people won't bother to read the book. It doesn't (shouldn't) cost the author anything. And if 1 out of 10 of those people wind up buying another book, they've done alright.
I agree the real problem with hoarding can be the mentality of the hoarder -- but only if it really does impact your enjoyment of reading, or otherwise gets out of hand. I don't think downloading a handful of books that you won't read is a serious issue. If you download 50 free books a day, 5 days a week,
that might indicate a problem.
