The issue here is there is no resistance factor like in the books. If Smaug uses the ability, the hero is controlled. I just see that as too powerful, and as far as uniqueness goes. Wormtongue did it.
Edain Team initially had him just taking over average units. What is wrong with this? Why are we trying to make it against heroes?
I mean, if we are to do a black and white list of heroes that should or shouldn't be controlled, then I suggest we list out all the heroes and say which ones could be controlled and which ones shouldn't.
To be honest, I would be okay with Smaug hypnotizing heroes as you guys say if we actually had a list of all the heroes he could and couldn't take over. For instance, I do not believe he could hypnotize any of the Ring Heroes that we have with the exception of Thorin, Boromir, & Theoden:
This includes Elrond, Sauron, Gandalf, etc. But I also don't believe he should be able to hypnotize any of the nazgul (loyal to Sauron, had rings, and no eyes). The following are a list of heroes who I feel would have total resistance to Smaug's gaze.
Imladris: Glorfindel, Elladan/Elrohir (can't focus on both at same time), possibly Arwen if you are saying she has the Elessar, & Cirdan
Gondor: Aragorn & Faramir (if going by the movie he resisted the One Ring).
Lothlorien: Possibly Celeborn and Thranduil are the exceptions but I would let you guys decide that.
Rohan: Everyone is free game
Dwarfs: I would say everyone is free game save for maybe Lord/King Dain
Angmar: Everyone is free game, remember Ring heroes with the exception of Thorin, Theoden, and Boromir fall into this category so the Witch King is the only exception here. Oh and Karsh
Mordor: Mouth of Sauron (magical sight and like the Nazgul, don't feel Smaug could undo what Sauron has done) & All Nazgul.
Isengard: Outside of Saruman, everyone is free game.
Misty Mountains: William, Tom, and Bert for the same reasons as Elladan/Elrohir & Smaug, otherwise everyone else is free game.
Others: Any evil Men save probably the ring heroes would be affected. The Blue Wizards would not be affected, Tom Bombadil, Goldberry, Radagast, Durin's Bane, and Erebor Gandalf would not be affected either.
If a list like this was implemented in the resistant factor, then I would be for the gaze of Smaug, you guys can debate whether you want the Hobbits affected or not, but Galadriel's light path would allow Frodo to have the ring so he would most likely not be affected.