Did We Miss Our Opportunity for Playable Ogres and Arrakoa?

First off, Ogres are the second-oldest race of the Horde. They're the only other Horde race to originate on Draenor, and while they didn't join the Horde until the Second War, when Gul'dan got Cho'gall (so many apostrophes!) to bring in his Twilight's Hammer Clan into the fold (Twilight's Hammer in the old lore was actually an Orc clan Cho'gall had taken over, but I think they've been gradually ret-conning it to having always been the Doomsday Cult that it is now - which is probably for the best.) The Ogres helped fight against the Alliance, but they were never as loyal as the Orcs and seemed to escape when the Orcs were captured at the end of the Second War. Indeed, the current Horde started as a really tattered remnant of its former demon-crazed glory, as the Ogres, Trolls, and Goblins who had supplemented them abandoned them (of course, later on, the Horde would get a different group of Trolls and a different group of Goblins, though to be fair, the Withertusk in Hinterlands seem to be from that original pact with Zul'jin.) There are, in fact, a handful of Horde-loyal Ogres in Dustwallow Marsh and Feralas, but it's not a playable race.

The Arrakoa do not have any history of affiliation with either faction. While the Alliance Expedition teamed up with Gruul to fight Deathwing in Outland (kind of surprising that Gruul was intelligent enough to understand the idea of teaming up,) the Arrakoa of our timeline were in horrible shambles. Of the three factions in Spires of Arak (Adherents, Outcasts, Sethekk,) only the Sethekk really survived the destruction wrought by Ner'zhul. A small handful of Arrakoa saw the Light and went to Shattrath to ally with the Naaru there, but this was a tiny group of refugees, and not the organized resistance movement that was the Outcasts.

Of course, the big thing these groups have in common is that they are from Draenor/Outland. The Ogres have a sizable presence on Azeroth, but the Arrakoa are almost completely unseen there.

Historically, World of Warcraft had added new playable races every other expansion, starting with the Draenei and Blood Elves in BC and then the Goblins and Worgen in Cataclysm. Mists of Pandaria was the expansion that upset that balance, adding both a new race and a new class.

But ultimately, these patterns are not as important as "what fits" with the expansion's concept. Wrath had us fighting the Scourge in a story that really mostly revolved around existing races (ok, the Vrykul were pretty prominent to be fair, but they're arguably quasi-humans... though no less different a race than Blood Elves are from Night Elves.) It made tons of sense to do Death Knights but no new races. Likewise, Mists kind of had to add Pandaren, but it also kind of had to add Brewmasters (which they made into a spec of the larger-umbrella Monk.)

Going back to Draenor would have been the ideal time to add Ogres and Arrakoa - both longstanding fan-theory favorites for new playable races. Ogres would clearly be Horde, and Arrakoa could easily be fit into the Alliance (or really either faction, though their color scheme feels more Alliance.)

Now, there's a very clear reason why they might have been hesitant to do new races. The ten racial revamps they did were probably not as time-consuming as creating ten races from scratch (the concept art was all done long ago) but it was still a ton of work. Both Ogres and Arrakoa did wind up getting new models, but they aren't the kind of super-detailed work the playable races got.

Still, I can't really think of another expansion where it would make sense to add these guys. It's very possible that we'll never get another Outland expansion. Ogres, to be fair, could fit in more situations given their presence on Azeroth, but Arrakoa would be hard to work in. That said, not all added races have had direct ties to an expansion's story. One could argue that Goblins were a big part of the evolving Horde war machine, but Worgen had absolutely nothing to do with the elemental unrest of the Cataclysm other than that they were a loose plot thread from vanilla that had never been dealt with.