But, to be fair, is there any particular reason why we should have expected it to happen by now?[The company also hasn't bothered to get around to properly introducing a Psionics class which has a longer history in the game.
Longer history, but not much history in a PH1, which was the initial litmus test. Psionics only occurred in a PH1 in an appendix, and not in the form of a class or even sub-class (like the Illusionist or Assassin in the same PH1) or quasi-class like the Bard in it's own appendix.
Even so, we do have the Mystic in the pipeline, with not one, but two appearances in UA. That's hopeful.
Conversely, the Warlord was a full class in a prior-edition PH1. Only one of them, but that was also true of the Warlock and Sorcerer.
And, of course, 5e was meant to expand the range of play styles the game supported, and to be for fans of each prior edition. Adding the Warlord would be in very dramatically support of both those goals. Indeed, it's hard to imagine another class addition that would have as great an impact.
In terms of actual expanded player options, D&D 5E is probably the single most dead edition ever put out since 1st.
5e has been out almost two years. The first 1e book came out in 1977, two years later, the third book had come out. 5e is ahead of that curve. Even if we're fair and count 1e from 1979 when the first three books had come out, all we had two years later were the Fiend Folio and Deities & Demigods, IIRC. No new player options. While, in 5e we've had SCAG and some on-line goodies.
But there hasn't been anything remotely approaching a new class introduced into the game yet.
There have been new sub-classes both in print (SCAG) and in UA, and the new Mystic class in UA, twice.
What if my fighter doesn't want to be distracted by the ruffian's ally? Note, not all thieves are pc's.
Y'know, there was a huge debate about that in the 3.x era. It was possible for a Rogue to flank with a fairly trivial ally, giving both the flanking bonus and enabling SA. At higher level, a contemptible enemy could provide flanking for a rogue, even though it did trivial damage and needed a natural 20 to hit you even after the flanking bonus, while the rogue would be inflicting very high damage. So, the thinking went, "why can't I just ignore the flanker, and defend fully against the rogue?"
There was no great answer for that.
I don't think it's particularly analogous, but it is an illustration of how thinking too hard about abstract mechanics, can create problems. And, it's also an example of 5e being 'better' than 3.x, both in the sense that Bounded Accuracy makes the situation less extreme, and in the sense that 5e is wide-open to a DM ruling to allow you to 'ignore' an enemy and thus avoid an SA (or not), in a way 3.5 (and especially the RAW zeitgeist of the 3.5 community) is not.
But after I think I'm done someone makes a post that completely misrepresents my position and I feel compelled to correct them. It's fine if you don't agree with me, but don't try to say I am saying something I'm not.
The medium can be tricky. You can come off as saying something you don't mean to. For instance, most of your posts on this topic come off as arguments to exclude the Warlord, rather than to assure that it be optional. For one thing, it being optional is a given, so that's going to contribute to that impression.
For another, your rarely bring a diatribe back around to that point.
Just because you say it doesn't make it true.
No, the facts make it true.
We just had a long list of Warlord powers from 4e that explicitly described the targets of said powers as admiring the Warlord.
We just had a long list that never said any such thing. Inspired, yes, admiring, no. Go ahead and try to find one. Or, before wasting your time, consider that those are all fluff text, which, in 4e, was separate from rules text, and could be changed even at the player level.
There is no requirement you feel a certain way about the Warlord to be inspired by him or accept good tactical advice, and you could always choose not to, in any case. Inspiration is a powerful but fleeting thing. You could be inspired to try harder in the moment, to show up a bitter rival at least as plausibly, as to please an adored hero, or live up to an annoying side-kick's faith in you, or save a non-combatant you're committed to aiding. That moment probably won't change how you feel about that character - unless you decide it does, of course.