Whether they're "needed" is really up to (1) the person/organization who wants the cert, and (2) whoever their customers are. There is value in validating that Bank of America Corp. is actually who's requesting the cert for bankofamerica.com, rather than (for example) someone else who managed to get the domain before the Internet got big. So, in the US at least, most financial institutions use EV certs for their websites (though one of my credit unions doesn't). How much that value is, is a separate question, but to many people and organizations, it's non-zero.
On the other hand, as you point out, some major Internet businesses do just fine with DV certs.