Here's what I found, and why I've decided to make an Elven Druid:
"The Runestone was an ancient monolith erected by the Elven Druids and inscribed with powerful runes of protection and warding." is an exact quote from Warcraft II: Tides of Darkness. It's referring to Quel'thalas when it states this. And don't think they're talking about Night Elf Druids, because they're nowhere near Quel'thalas and weren't mention until Warcraft III.
Also, in the Botanica, several of the Blood Elves cast spells similar to Restoration Druids, and not only does High Botanist Freywinn wear the Tier 1 Druid Set, but he also casts Druid healing spells, creates plant spawns, and even turns into a Druid Tree Form.
It also states that High Elves, Half Elves and Blood Elves all possess the ability to learn Druidism. Once the power is in the bloodline, it isn't removed.
Just to clear things up, I won't be a full on Druid either. Just a Wildcaster. So I won't use shapeshifting forms because if there is a bloodline that holds Druidism it wouldn't be that strong (Also because game mechanics don't allow that), I'd only be using simple healing spells. I also chose a Monk class and a Mistweaver spec because I felt that'd be best for the appearance and style of a Druid.
I've already started RolePlaying on this character and everyone who's questioned Elven Druids are fine with it once I give them the reasons.
So let me know what you all think, and if you'd allow this in RolePlay!