In a lot of occasions I dragged a file into a page, believing that the page was cool enough to have a HTML5 drag&drop handler. In a lot of cases I was wrong, the page wasn't that cool.

I think that in these cases (lack of a drop JS handler) we shouldn't navigate the tab away as a default response to a drag&drop.
All the times it happened (mostly on bug trackers) to me I was filling some form I ended up losing some of the state of the current tab.

I am not a UX expert, but I find the use case of navigating to something by drag&dropping very unusual.