You mean aside from the plausible ones that they forewent in favor of BE and Draenei?

Ogres were already around, have ties to the Horde, and could have theoretically been given reason to join in the Outland activities with the initial intent of freeing their race from the Gronn. Wouldn't have been that much of a stretch.

Not that I'm saying ogres would be a great player race, but it wouldn't really counterindicate existing lore.

Still, it probably is best if they remain where they are on the player races, at least for a while until some other NPC races are more fleshed out over the duration of an expansion or two and have enough preexisting lore and faction relations to make for potential candidates.

In other words, no more playable races joining the factions six months after meeting them for the first time.