See +Per Abrahamsen
's comment. Dropbox doesn't do half of what Drive does as far as showing thumbnails and previews, or the ability to share files with others. These permissions do seem excessive at first, but they're pretty much necessary to prevent people from suing Google for doing what it technically needs to do to provide the stated functionality of the service.
An argument could be made that Drive does too much,
but those people would be missing the point of the service. Drive isn't just a cloud-based storage and synchronization. Like Docs, it adds a social element to allow collaboration.
That said, I probably won't be using Drive in the foreseeable future. The lack of a Linux client is certainly one major flaw, though Google is pretty good about supporting Linux. But I simply don't need any extra ability to share files. I already use Docs to share documents, G+ to share photos, and YouTube to share videos. Toss in email, and I already have more than enough ability to share files. What I do
need is the ability to backup and synchronize important and sensitive files, and for that I use #SpiderOak . It's very secure, separates the backup and synchronization functions so you can back up a file or folder without syncing it with other computers, and it lets you select from the files and folders on your computer rather than giving you a single folder for everything you want to sync.
What I'd really love is a pure synchronization program with no online backup and therefore no data cap. AeroFS looks like it would be a possible solution, but it's still in a closed beta.