Gonzalez was always an in-line tight end (and probably the best ever) and Gates has been for most of his career, especially after he found blocking.
I do get what you're going for, though. Hernandez is a new breed of player because guys are just getting bigger and faster. If anything, he's more comparable to a slot wide receiver like Welker than he is to any of the guys you're comparing him to, he just weighs nearly half a hundred pounds more than most of those slot guys. It's not even really fair to call him a tight end.
And, for what it's worth, Gronk's a better downfield receiver than Hernandez is. He's hardly just a 'tough catch over the middle' guy, and nor was Gonzalez in his heyday. Hernandez is just substantially more dangerous after the catch since he can make people miss rather than just trying to rumble over people.