Yet Zandalari and Kul Tiran also have those animations, and their druid theme is totally different from Night Elf's druid.
There are also other things like Holy Void Elves and Shadow Lightforged that in Lore they aren't supposed to exist, but in gameplay we can just switch specs on our free will without nothing happening (no explosions, no character death, nothing).
If Mechagnomes come as an allied Race, the classes Shaman (eletroshock), Druid (transformer), Mage (high intelect) and Hunter (robotic pets) are probably the ones that best fit the race. Tinker class would probably fit them as the "best in slot" option.
PS: I would only play them if Tinker Class becomes available and if they would be one of its races. I already have too many alts right now.