The following has my vote:
BM has a LOT of talents that you would never pick because the tuning is bad but there’s no tuning that would ever make you pick Kindred Spirits.
This is a 2 point talent that gives you and your pet an additional 10 max focus per point (not focus regen mind you just max focus) at the top of the tree that’s so bad they allowed you to path around it. It’s pick rate is actually 0% and it could be buffed by 5,000% and no one would ever pick it still.
hasty provocation is actually VERY useful. i like to use it on spiteful weeks. i can taunt the ghosts and they will continue toward their original target (not tauntable) but at higher speed. it’s hilarious 
Monk speed taunt is super useful in many fights.
On Mythic Raz for example, we’d have me speed taunt her on pull, both to get her to the edge fast (which you need to, on Mythic) but also so she could bonk me and trigger Ret Aura since I wouldn’t have shuffle up.
Answering the thread title, the most worthless talent on any talent tree, to me, is anything that makes you use a ranged weapon when you’re specced into survival hunter.
I noticed this and thought that the game makers must have run out of ideas.
It didn’t make any sense to me.
That’s the 1st one that came to mind. Others probably have better answers but still, I’d like to know why so many marksman talents are available to survival hunters when survival uses melee weapon?
Maelstrom weapon and flurry for resto/elemental.
Like why are these even in the ‘shaman’ tree when those are 100% melee talents? Should just be baseline enhance.
Another one that really bothers me is control undead for unholy.
You quite literally have to go around it to get to the talent you need.
Brewmasters and Windwalkers have to put a point into Soothing Mists (which is a CHANNELED HEAL) to get to Improved Roll. 
I want to emphasize the CHANNELED HEAL part. Vivify might be bad, but you still put it on your bars as Brewmaster/Windwalker.
Nobody even bothers putting Soothing Mists on their bars, because you’ll never, ever cast it.
Shackle Undead
Having to take a number of talents you cannot use while tanking to get to talents that used to be baseline. Also, having to choose between two talents we used to be able to have both of, and used to use them both.
You know… primal strike as a elemental shaman is an absolute waste of a button. It’s the fastest button I remove off my bars when making a character ever.
Shackle Undead and Banish.