My theory to why some of the Tauren have ditched their earth mother and converted is this: In the book by Christie Golden "The Shattering", Anduin gives Baine Bloodhoof a paladins mace as a "gift". Unless there is some reason unknown to me to why taurens can be pally's, my theory is that Bain ran home to TB with his new holy hammer and said "alright guys, who wants to convert? i got myself this holy hammer here, lets smite down some foes with this sucker". That is the only indication I've seen so far of to why taurens can be pallys, unless there is some hidden lore I haven't seen, this is how it is guys.
Other possible theories include: "Because we can", "How come Ally gets pallies, we want to be them", "Blizzard accidently added tuaren pallys and have yet to notice the bug", "Because gods are cooler than earth mothers", and "just because it makes more sense for a holy cow to run around smiting people than it does for a gnome to pick up a bow and start being a hunter".
But seriously, is that the reason? Is because of Anduin gave Baine King Magni's holy hammer part of the reason Taurens can be paladins?
Discuss.......or insult my lame theory, the choice is yours.