Mearls really went out of his way to INCLUDE anything/everything fans of the Warlord said the game needed the Warlord /for/. The game needs to be able to model an Inspiring Leader! Ok, here's a feat /called/ Inspiring Leader, it's completely passive & blah, yet even a tad broken, there, you can't ask for that any more, you have it, done, leave me alone. You need to be able to rally allies to return to the fight! OK, here's a BM maneuver called 'Rally,' it's explicitly useless for getting a fallen ally back into the fight, but it's called Rally, so you can't ask for that any more, you have it, done, leave me alone. And, Commander's STrike, it was iconic! OK, here's a BM maneuver you can use half as often as an encounter power in 4e, that's not much like it at all, but is called Commander's Strike, so you can't ask for that any more, you have it, done, leave me alone. That's still not a martial leader. OK, ANTOHTER fighter sub-class, what's coming out next? SCAG? OK, Purple Dragon Knight, obscure PrC, it's totally martial, it leads, (Kobold Press, make that happen!) we even slipped in a little-w 'warlord' typo, so you know what it's for, there, you can't ask for that any more, you have it, done, leave me alone. There's still the tactical genius concept who helps his allies out that way. Way ahead of you, also in SKAG: the Mastermind, a Rogue sub-class with juiced-up Help actions, there you can't ask for that any more, you have it, done, leave me alone. We need the Warlord as a martial class that fills the support roll. Just re-skin a Valor Bard or War Cleric or Paladin, they're good in melee, great at support, just close your eyes and pretend it's not really magic! But none of that is anywhere near a Warlord. Fine! Fine! Here's half-finished fighter sub-class that's actually straight-up called a Warlord, there you can't ask for that any more, you have it, done, leave me alone.Not including the Warlord put that out as an obvious lie to 4e fans.
Why not just a Warlord /class/?
Oh, it's too narrow a concept, couldn't possibly have enough sub-classes to fill it out, can't justify adding it to the game.
Feats: 2 (inspiring leader, martial adept)
Maneuvers: 2-6, depending on how generous you're feeling (Commander's Strike & Rally at a minimum).
Sub-classes: 3-8 (Fighter: PDK, BM and Rogue: Mastermind, at a minimum. But each of the following have also been suggested as Warlord stand-ins: Fighter: Cavalier, Samurai; Cleric: War; Bard: valor; Paladin: Oath of the Crown)