As far as I'm aware, their growth (primarily) comes from people inviting each-other and they're obviously device/OS agnostic. Yes, the pricing is way different but we shouldn't assume that's the major driver for most people.
Simple: Everybody and their mother already has a Google account.
It's a lot easier to tell someone to use Google Drive instead of creating an account on Dropbox and installing their software and going through the whole rigamarole.
Unlike SkyDrive et al, Drive is aiming right at the throat of Dropbox and Google has the money to make sure it succeeds (see G+).
Dropbox doesn't have to compete on price (I don't think it's as big a factor as everyone makes it out to be), but they do have to think about improving the feature set.
If Dropbox doesn't respond, they do so at their own peril.
Applying the principle of anecdote==fact, I have to disagree with the first point. I tried for ages to get my parents to use Gmail instead of Hotmail and failed miserably. Drive would actually be great for them when sharing photos.
Agree with your other points though. The OCR and search sound like great things so yes, you've convinced me that Dropbox has to compete on features somehow.
As far as I'm aware, their growth (primarily) comes from people inviting each-other and they're obviously device/OS agnostic. Yes, the pricing is way different but we shouldn't assume that's the major driver for most people.