Previously, most recolors used to come from the same source, and that was cool. They are a tool to offer cosmetic choice and to make people feel more unique even if a lot of them use the same mount. For example, earning exalted with Netherwing opened up 6 recolors for you, you could get any or all.
Later on, recolors of very cool, "flagship" mounts started going to individual sources, and this also works well because it strengthens the identity of each individual mount. These are mounts that would suffer from putting 6 or 12 of them on sale at a single "dragon breeder" or equivalent; mounts like the various Drakes, and especially the Proto-Drakes and the Cloud Serpents.
Then, in WoD, we have 12 boar variations, and each and every single one of them has its own source, or at least its own individual grind. For Horde players, it's almost as bad with wolves - there are 10 of them total, to be obtained individually.
The problem is that neither boars nor wolves are cool enough to be a "flagship" expansion mount. You can go on saying "Oh, I got a Thundering Onyx Cloud serpent!" and "Oh, I got a Heavenly Crimson Cloud serpent!" and still be excited, but you can't do the same with: "Oh, I got my first tan boar, how cool!" and "Oh, I got a blue boar now!" and "Oh, oh, look at that rep and that rare, a brown boar, and a slightly darker brown boar! Yay!".
It just doesn't have the awesome factor to keep people interested over so many subsequent recolors. Rylaks might have, as there are 14 unused models, both armored and unarmored, aside from the store and pathfinder ones. Hydras? Maybe, but they never made it into mounts, although at some point they had a /mountspecial animation. Just like a "boar farm" rep with 10 recolors would have been cool and wholesome. As well as frostwolves giving more wolves instead of spreading them around.