More storage space is long overdue

[Seraphor]

That's the funniest thing to me. Defend it how much you like. But how can you say [server limitations] one moment but allow [every] player to buy up to X(not sure how many) and that somehow doesn't cause an issue?

I don't care what dev wizardry is at work behind the scenes. Not do I need to. I'm just a player. All I see, though, is that it somehow works for players who pay more. That's all I need to know.

It IS a server strain issue, in that having all of those inventory slots accessible (constantly loaded) isn't viable at the same time as battle data, so in instanced duties or in world zones, you cannot access your retainers or glamour dresser.
That's why these things are only accessible in towns.
The Chocobo saddlebag is an in-between in that it's available on world zones but not in instanced areas. (which was added in 4.2 btw, so that's our inventory expansion)

That fact that those retainers are predominantly behind a paywall is a separate issue that is neither affected by nor would alter the fact that additional inventory space is a server strain issue.

In other words; people buying "additional inventory space" aren't getting around the "server strain" issue, because retainers are still separate inventories that aren't always accessible.
These are two separate issues that you're mixing together.

Another issue adding more free retainers brings is how many items you can sell, and how many ventures you can send your retainers on, so I don't think "more inventory space needed" is a good enough justification (for them) to give us more free retainers. Plus changing the number of free/paid retainers at this point probably causes issues for those who have been paying for additional retainers. Do their paid retainers convert to free, or they gain more retainers? Do they cancel or refund the retainer fee? etc. (all of which results in a very real loss of income to them, akin to reducing the subscription price, you can call it 'greedy' if you like but it would be a stupid business decision to do this)

Instead, if inventory space should be expanded, then the best candidate for it is probably expanding the Chocobo Saddlebag. That would give us more room available in non-instanced zones, without impacting the content that matters. Although it may still affect lag in world zones which could make hunts and such even worse than they currently are.

[Packetdancer]

That's the funniest thing to me. Defend it how much you like. But how can you say [server limitations] one moment but allow [every] player to buy up to X(not sure how many) and that somehow doesn't cause an issue?

(Leaving aside the excellent resource instanciation explanation above...)

Because in many companies, devs don't just get to unilaterally add features if they have a measurable impact on resource use and/or operational cost. And if allowing everyone to have, say, 500 more storage slots universally would add up to X amount more storage and thus require adding Y amount of cost to the server budget, that can be hard to convince the company's finance team is a good change; they just see numbers, and they'd see one number going up there where they don't want it to.

Whereas if you can sell the 500 more storage slots so that the extra Y cost is covered by those sales, the finance team doesn't flail around in a panic about increasing the costs. (At least in my own experience from having worked in the industry, and still being in touch with many former co-workers and old friends who still are suffering through crunch time.)

It's dumb, yes. But a lot of corporate politics behind-the-scenes in game development boils down to what I would define as "dumb". And based on my own experiences, I would not be shocked if that was exactly the logic there behind making additional retainers purchasable but not just giving everyone 10 retainers for free. "Not everyone needs this much storage, and the ones who do will pay for the server bills by buying it!"