Well for starters, all you did was list a bunch of jobs. You included zero reasons why any of those jobs listed are more "interesting" options. It's entirely subjective, and to prove that point, personally I find all of those jobs you listed to be uninterested as hell or just jobs that have an incredible amount of overlap with existing jobs.
Red Mage may well be more demanded than Samurai, but I still lean towards SAM being the most requested job. It's been mentioned far more from players and the devs than RDM has and not a live letter goes by where people aren't screaming for SAM in the chats.
Most of these jobs you're asking for have no where near the appeal or popularity that SAM/RDM etc. have. Why, from a business perspective, would a company spend time to make such a gamble that maybe people would like something so obscure? Especially when they have options that they know for a fact have a lot of pull.
And yet you say this in a thread where the OP posted a tank version of Samurai (Not a sword DPS) that also had mechanics unlike those from FFXI. So you're just in denial that it's possible to take the job and make it something unique because of reasons proven wrong in this very thread? Ok.
Funny cause Warrior uses a two handed weapon and has an even better Parry cooldown than DRK. I'm tired of seeing people say DRK is some be-all-end-all to parrying as a mechanic. That's like saying they shouldn't add another tank if it has cooldowns that flat reduce the damage they take (Of which all tanks have some variant of).There's also the question of how would it be distinguished from Ninja if Samurai would be a DPS or Dark Knight if Samurai would be a tank. "I want a tank in heavy armor with a big sword that relies on parry". Uh, yeah, we have that, it's called Dark Knight, and it's one of the main reasons why we know that parry is almost a negative stat in terms of itemization. "I want this Japanese-theme job as a DPS". Like Ninja, which already kinda works? There needs to be something more that sets it apart from jobs like Ninja or Dark Knight, something to make it stand out and feel both special and unique compared to the other jobs in its given role and grant it a reason to exist in the game. So far, I have yet to see such a reason. I would admit that some have gotten close, including the OP of this thread, but still not there yet.
Again, this thread is about Samurai as a tank so your yammering about SAM dps overlapping with Ninja is pretty moot. SAM would have little overlap with DRK, thematically and animation-wise anyways, even if it had emphasis on parrying (Or more likely, counter-attacking.) There's precedence from past FF games to have Samurai create barriers on themselves to mitigate damage, as well as the ability to parry/counter magical attacks. There's also the option to make the job dual wield, which would eliminate even more of any kind of potential overlap from DRK. (Not that there needs to be, by having DRK use their sword in an Ox stance gives it a very distinct silhouette that is unlike what we'd get with a Samurai holding their sword. On top of DRK's animations being very weighty and slow, again unlike how a Samurai would likely swing and attack with their weapon.)
If you can't seem to think of how vastly different a Samurai could be then that's on your lack of imagination.