Canards have another job - to keep the air going over the wing rather than smack into the underside in high angles of attack.
And as for how useful thrust vectoring is, ask the folks at
Lockheed Martin who put an F-16 with thrust vectoring up against its conventional cousins (often with odds not in favour) and it still held its own. Now imagine what an aircraft designed with thrust vectoring from the word go could do.
(See also: F-15 ACTIVE, X-31)