Dropbox could identify users who are more likely to need to resurrect a file (either because they frequently delete files, or because they frequently resurrect them), and offer them a discount on packrat.
After all, the man most likely to value hurricane insurance is the man whose house was just blown over by one.
While I agree with you, have you ever tried explaining svn or git to somebody non-technical? It's not at all easy. Now try and explain to them how to commit and push files. Where does their repo live? How do they get at a file from another computer? How do they share it with somebody else?
There's value in a solution that makes copying your data to multiple systems drop dead easy and automatic, and Dropbox is in that niche. If you need more {robust|reliable|scalable|detailed} file history, it's not right for you. But you can bet there are tons of people in Dropbox who delete things a lot (just like I have met people who store "important" email in the trash folder)
I can't say I've ever noticed this feature before on Dropbox. I came across it while searching for the correct use of the word/term packrat (with or without hyphen). Nice use of the word on Dropbox's part.
After all, the man most likely to value hurricane insurance is the man whose house was just blown over by one.