Why can't he play a Battlemaster with the Rally maneuver and the Healer + Inspiring Leader feats + take a background with the Herbalism Kit proficiency to make healing potions? Or is there something besides healing ability that he is looking for?
Actual herbalism/Healer/magic-potion stuff may be well outside the character concept. Feats may or may not be available in the campaign, and even taken together with Rally, are insufficient for the sort of support role in question. Finally, the Battlemaster, like all Fighters, is strictly a DPR character, which is also at odds with the role envisioned.
I would leave if the Warlord was forced back into the game.
The Standard Game has been established since the PH hit the shelves, and, even if it's remotely possible some bits of it might get radically errata'd, it seems vanishingly unlikely that whole classes would be added that way.
You do not have to worry about the Warlord being 'forced' back into the game.
The Warlord, as a Class, encapsulated much of what I didn't like about the last edition into one nutshell. It was a contrived Class that had no archetypal role in a narrative sense, but merely existed to fulfil a niche in the rules system.
The Warlord archetypes are quite familiar from genre, just because D&D had so long failed to adequately accommodate them, doesn't mean it had no place in the game.
The term 'Warlord' is pejorative in root usage
False. Even if it were, so is Warlock and to a much greater degree, and Warlock is objectionable to some on the basis of RL religion. Same, to a lesser degree with Sorcerer and even Wizard. If you hear 'Cleric' in the news in recent years, it's probably in reference to a fanatic exhorting zealots to violence. Those same zealots and their less radical sympathizers would find the crusader implications of 'Paladins,' and, due to it's use by US Special Forces, 'Rangers' provocative, as well.
Really, if you did away with D&D classes on the basis of such trivial objections to their names, we'd be left with nothing but the Fighter.
while the notion of a 'leader' class denoted rank over other PCs.
False. The explanation of the Leader Role made it clear, explicitly, that such was not the case.
It undermined the functional roles of Fighters (why shouldn't they be Lords?).
Fighters never handled that role well, though. The 4e fighter was re-focused into a much narrower role, that of the traditional melee tank, formalized as 'Defender.' In a sense, you could think of the Warlord and Ranger as being broken out from the 1e and 3e fighters, respectively. The fighter was one class forced to cover virtually every non-magical archetype except thief/assassin for a long time, and that with few class features. It was never up to the task, and splitting it into three classes gave a great deal more choice and focus to players interested in something other than a caster. If anything, 4e didn't go far enough in introducing new martial classes (or splitting them out from the Fighter and Rogue, if you prefer) with more and more interesting concepts and roles.
The healing via inspiring words was not a sole issue of the Warlord Class alone, but it tended to accentuate a lack of realism in the rules rather than mask them.
True, the lack of realism that is brought up has always been there. Whether it's really being 'highlighted,' or whether the foes of the class just selectively attack the system's perennial lack of realism within the context of the warlord, because they realize they have no valid objections to the concept itself, is really moot. The system lacks realism, objecting to a class because it lacks realism is nonsense.
I would support trying to develop a Fighter subclass - like the Battlemaster or something else - to try and create a more strategic, tactical style of Fighter.
The fighter class is functionally even more focused in 5e: it's strictly a DRP class, so there's really no room for that. Any fighter archetype is just going to be a few tricks tacked onto DPR. New 'martial' classes really are very much called for. 5e has a much more open class-design philosophy, so there's lots of room for them.
I agree. There was something always off putting about the warlord. Especially the lazylord.
That sort of vague personal reaction is really the only thing that can be honestly said against the warlord. Yes, some people don't like it for reasons they can never justify (and don't /need/ to justify), but those people need never play one.
The fighter is a romper-stomper of a combat machine. But some guy shows up and starts giving order and now the fighter is better at his job?
Yes. Good leaders help people do even better those things they are already great at. IRL. Heck, it's more realistic for the Warlord to make the fighter better at fighting and the wizard better at wizzing than, than it is for the wizard to exist in the first place.
Eh... I'm doubtful "Inspirational Commander" is a more prevalent/well recognized/popular fantasy archetype than the "Berserker".
Perhaps in so many words. Warlord certainly wouldn't be any less common a description of fantasy characters than Berserker. "Inspirational Commander" seems a little more likely to be the hero than "Mindlessly-Raging Killer," too. It's also narrower than the Warlord concept, with the Inspiring build being only one of 6 official ones, plus the oddball 'lazy' builds - and it's not like there isn't the potential for more.
I'm intrigued by this... can you name 5 characters from fantasy stories (not historical)
What, history not realistic enough for you?
that would fit the Warlord archetype?
Can you name 5 that fit the glowy healing by touch in every combat D&D Cleric archetype? The 2e PH tried to come up with examples from fiction & myth for each of the classes. The best they did for the mace-wielding, spell-casting Cleric was Archbishop Turpin, who used Sword & Lance like all the rest of Charlemagne's Knights, and never cast a spell.
A Search of Amazon Books for Warlord under the heading of sci-fi/fantasy, finds 267 books with Warlord in the Title, itself. The same search for Cleric returns 44 (10 of the first 12 bearing D&D logos). Amazon seems to think John Carter of Mars and romance novels are 'fantasy,' though, so take that with a grain of salt.
Someone whose words of inspiration give tangible benefits of healing and buffing to their adventuring comrades but they as well as their source of inspiration are not themselves mystical/magical in nature or in their use of said inspiration?
How many wizards can you name from fiction/myth/legend who prep spells in the morning and expend them like grenades all day? None outside the works of science-fiction author Jack Vance and actual D&D novels.
Were those two archetypes being compared to the warlord?
They're both D&D classes, so, yes.
Except none of these (except maybe the MMA example...shrug) are forcing movement the way D&D has/had it.
In broader terms, on-the-fly tactical positioning* is something done independently by each (at least quasi-intelligent) participant in a battle once the battle has begun and the fog of war makes giving and receiving orders difficult if not impossible.
* - as opposed to pre-planned tacitcal positioning set up before battle commences, in cases where such can be done.
Another aspect to keep in mind is that in many ways we're fighting the system here: a rigid turn-based game doesn't do "fog of war" as well as it could, or probably should, nor does it reflect the fluidity and randomness of melee very well. There's ways to tweak it so it does these things a little better; I see the ability to tactically force-move people as a step in the wrong direction here.
Things like the 3.x 5'-step, shifting, flanking, marking, 'forced' movement &c arguably do a fair, very abstract, job of modeling just that sort of thing (and similar things) without drowning in detail.
Within the fluidity & randomness of melee, the confusion of the 'fog of war,' the chaos of the 'press,' or whatever, you can very easily have an individual end up somewhere he rationally very much would not want to be, had he perfect knowledge of the battlefield and his opponents' intent. A skilled combatant taking advantage of that to slip away from a foe, get closer to one, give an ally a chance to slip away, attack from a position of advantage, etc, etc, is perfectly reasonable. To avoid drowning the system in the complexity of multiple contested checks, even more detailed positioning, simultaneous action declaration, and other impractical mechanics, modeling such things abstractly is obviously desirable - and mechanics like the 5'step, forced movement, flanking, marking, and the like seem perfectly good ways to do so.
What alternative mechanics would propose?