I used to love that spell! I loved giving my shaman buddy prowl/solar beam and there were some neat spells you could get from other classes too.
It was always scuppled by the class balance system at the time, which pretty much tried to make everyone equal; if symbiosis has been powerful, everyone would have brought Druids over other classes.
However in BfA class divergence and class niche specialities are a thing again. So why not bring back Symbiosis? Who doesn’t want to get a little symbiotic with their friends?
But maybe streamline it a bit more. For those receiving it, healers could get CR, tanks stampeding roar, DPS tiger dash, ranged Moonkin disengage.
More consistency across those receiving it would make it less of a choice for them about who gets symbiosis, and more of a choice for the Druid based on what ability you want.