the Horde has 3 races which can become shaman, orc and troll and goblin, while the alliance has just 2, draenei and dwarf, these 2 races arent very popular either,
first of all, alliance have 3 paladins as well. the paladin is the alliance trade mark, while the shaman is the hordes trade mark. and no race atm, would fit for paladin on horde side. neither would any race on alliance side fit for shaman.
there will most likely never be an equal number of paladins and shamans, because the majority of the horde is based around alot of shamanism, while alot of the alliance races are based around the holy light.
human shamans would be retarded. and your argument about the races not being very popular, is not blizzards care. they dont care what races we like, and they dont give the races their classes, depending on which race we like the most. its based on lore.
edit: horde has 4 races. you forgot the tauren. but thats because orc, troll, tauren made up the old horde from WC 3 which was all under the race (orc) and they're all spiritual, making either of these 3 races not shamans, would be a terrible idea.
though i dont always know why goblins can be shamans... but i suppose it could work. its an odd combination though.
A elementalist is a person who bends the elements like fire, earth, thunder, water and air
, if you take a more tribal elementalist >.> you have a shaman!!!
this happens to be wrong as well, as shamans dont BEND the elementals. we befriend the elementals, they help us willingly. we're helping each other. we respect the elements. we're not warlocks who just uses the elements for manual labor.