In the lore, everytime I see a Druid is either growing vines or shapeshifting. I don’t recall seeing any Balance Druid, neither Malfurion who just opted to fight Saurfang in base form.
I am surprised, with how amazing the astral spells are, but I’ve seen Priestess of the Moon using Balance spells in lore more than the Druids.
is there anyone or any hint towards it in the game?
Well when a night elf meets a chicken, and they get a funny feeling deep low. Some unnatural things come out of that kind of union.
I see. This makes Kultiran Balance Druids quite creepy, if by… that requirement we go.
Different strokes for different folks;)
There might be something in here.
Balance Druid lore: these chicken things. had a thing with the moon. and the sun. and so… with a two things to keep track of they started sitting on a wire. and casting edible slow mushrooms… or somthing. which lead to their base controls always needing to change in order to balance the unstable nature of a chicken that could boom one day or be oom another. the chasing after the perfect celestial alignment lead them on a journey to find a way to convoke the spirits into giving them the power to do it all inside of an eclipse window. 
and just like that, they brought balance to the force. as all things are now balanced. every class has some special move that can rebalance the field of battle.
What more lore do we need other than being awesome?
Druids have always had a connection to the sun and moon, specifically Night Elves and Tauren. As both the sun and moon play a part in nature and the balance of life.
Both races have a cultural connection to the sun and moon, even the non-druids.
Tauren were actually the first druids before the Night Elves, though it was before they evolved into modern Tauren.
"The tauren are the descendants of a bovine race known as the yaungol. Several millennia before the First War, the yaungol roamed central Kalimdor and lived in peace with the demigod Cenarius, but were eventually driven south due to not wanting to share hunting grounds with the trolls. There, the yaungol were enslaved by the mogu empire and twisted by the mogu flesh-shapers. Though they eventually regained their freedom along with the other slave races during the pandaren revolution, much of their ancient cultural heritage had been lost. Heated arguments led many yaungol to migrate back north. While one group traveled as far north as the Storm Peaks, where they took up the name taunka, the other group settled in the balmy areas surrounding the Well of Eternity.
There, they reunited with Cenarius and rediscovered their ancient traditions. Those who studied with Cenarius learned the druidic magic of the natural world, while others mastered the art of wielding shamanic powers. The energies of the Well soon began to change these yaungol into a new race, who would later take up the name “tauren”. The taunka, tauren, and yaungol retained some contact with one another for many years, but the Great Sundering finally shattered the connections between the tribes."
In regards to Malfurion:
“According to tauren mythology, Cenarius (the patron for all druids) instructed them first in druidism as recounted in their myth Forestlord and the First Druids. As it stands, the night elves claim the first druid was Malfurion Stormrage, an idea challenged by the tauren beliefs. This is clarified in Chronicle. Cenarius did live among yaungol, the ancestors to the tauren, when they settled near the Well of Eternity between the 12,000 and 11,900 BDP, but Malfurion was the first to be trained in the ways of the druid, around year 10,000 BDP. This is why Malfurion is referred to as the first mortal druid. The yaungol could thus be compared to the early humans who used crude nature magic, a primitive sort of druidism, like the Gilnean harvest-witches. A similar case can be said about Valewalker Farodin, who was a student of an ancient order of keepers predating the druidic traditions of the night elves, and not full druids themselves.”