I think this limitation is actually fundamental to Dropbox's (and Google/etc) pricing model. Only a small subset of users can fully utilize the space they pay for, which means the remainder of users are more profitable. If the average user consumed 1TB, or if pricing was by usage rather than tiered, I'd expect the price per GB to go up.
was downvoted for my previous comment, let me clarify, books are a known vector for bed bugs. libraries are facing this problem all over. a friend of mine worked at the columbia university library and had to go through freezing process on returned books.
all i'm saying is, books cost hardly anything, libraries have ebooks. why expose yourself to this problem?