There are plenty of heavy melee Ethereals, they just prefer their glaive-blades to running around with two-handed weapons. And there are probably more melee Ethereals than there are spell-casters. It's no different from how there are no real Night Elf "warriors", they're sentinels. Every race can pick up a sword or axe or shield and slam it into things, that's why every race can be a warrior. And to argue that Ethereals wouldn't make a good race because they're "business men" is just silly. The goblins are far more concerned with money that the Ethereals. A typical Goblin is willing to sell out anything, their friends, their honor, you'd have a hard time finding a goblin that would rather fight than pay their way out a sticky situation.
Ethereals on the other hand are more concerned with profit than Goblins. They'll gladly stand and fight you to keep their profits, or to kill you and take and sell whatever you might have on you. They're raiders and thieves who trade, not business men. Not to mention they have their own pride and commitments they'll gladly fight for. When you show up in Mana Tombs and start killing Nexus-Prince Shaffar's forces, he doesn't grab his loot and run, he takes it as a personal offense and meets you head on to make you pay for what you've done.
It isn't bizarre, because as I've already mentioned the old races aren't a priority. They're something the art devs work on when they have free time and aren't busy working on models and artwork for things like Throne of Thunder, the new 5.3 scenarios, Siege of Orgrimmar, and probably at this stage, the next expansion. They aren't going to stop and say "Oh hey, let's not add content to the next expansion because we're going to work on old races instead", they're going to say "Hey, we could probably finish some of the old races while working on the new content, and if the old races don't get finished, it's fine because we've already said they aren't going to be released all at once, they're going to come out when we get around to it and they're finished."