I don't mind having that as the default, but at least give people an option to select files the old-fashioned way, and make it easy to find within ~5 or ~10 seconds of looking at the page...
Imgur does this well, if you ask me - support for drag & drop, menu, and copy/pasting URL.
Edit: It would be useful to make an addon that adds a contextual menu item for "Drop file here", which raises a file selection dialog and delivers the result to the drop zone. Essentially it would be the inverse of this: https://addons.mozilla.org/en-US/firefox/addon/ez-drag-n-dro... I don't currently have the time to write it.
There's no expiry date on a productive workflow.
Why not ratpoison?
my bad. it's still very alive.
But in general, that's still awkward, and enough of a (mental) hassle that I probably won't bother if it's just someone who wants me to check their site out. So my advice to any web designers would be to make sure your site is functional even without the flashy add-ons, the same way you would make sure your site is functional on all browsers/operating systems.