Originally Posted by
Vaedan
I will elaborate my PoV a little.
When we are talking about classes, there are gameplay classes and lore classes. In some cases, these two categories match, for example Human Paladin matches original Silver Hand paladin archetype. There are lore classes which can be represented to some degree with gameplay classes without notable differences between the two, for example Draenei Paladin as manifestation of Draenei Vindicators. In fact, draenei didn't came to be paladins as humans, they are not essentially the same thing, but they are so close that you can impersonate Vindicator by paladin and leave it as it is, without much other questions. Then there are lore classes which can be represented by gameplay classes, but at the cost of some characteristics of that class, for example Zandalari Paladins as Zandalari Prelates. We all know that Zandalari draws their power from loa, so their source of power is different to humans, draenei, elves. Zandalari Prelates are their own thing, but their uniqueness is not supported by paladin class.
Now, back to the topic. Alliance represents faction of iconic paladins, as said. Alliance gave birth to Silver Hand and when we look at paladin class, it's gameplay and visuals have been modeled around it. For that matter, Alliance races shows that they came from this origin and I don't think there is anything more you can add to reinforce this. Alliance have also access to draenei and lightforged draenei paladins, which opens them an option of more exotic paladins, which fits in the theme of the class pretty well. To sum up, Alliance have access to standard archetypal paladins and also have option of some more outlandish ones.
If you look at the Horde, you can see that all their paladin races didn't have their origins in Silver Hand, which was chosen to be made as an archetype of gameplay paladin class. Blood elves started as Blood Knights, which drained Light from Naaru, basicly abusing the Light for their own needs. Tauren paladins are Sun Druids who took more warlike approach of their teachings. Zandalari paladins are chosen of Loa of Kings and they draw their power from it. We can see that all of them does not match lore and gameplay class. It feels weird to have tauren or zandalari paladin throwing hammers, reciting from holy librams while casting heals, etc. Horde has pretty great access to more exotic paladins, but they are pretty limited when it comes to good oldfashioned Silver Hand paladins. I admit that Blood Elves evolved to fill that role in the Horde lately and the game shown us that even blood elves joined paladin factions.
I'm not sure if I explained myself better, but all those things I just wrote are my personal opinions and you are free to disagree. For me, the list of Alliance paladins fullfils what I expect from the class on that faction, and while I won't deny that there could be more options to be had, I am OK with the way it is now.
On the other hand, when it comes to let's say druids, alliance side is centered mostly around cenarian druidism with only kul tirans displaying anything different, while Horde have cenarian druidism (both tauren races), dinomancy (zandalari) and loa worship (darkspear).