The Formula won't change

[Kohashi]

Money. That's the difference

Without a weekly cap, the already sparse content would be well stretched beyond its breaking point. It means stuff like say, the 24 man releasing next week has literally zero value. After all, how can it serve as catch up if there isn't a tomestone cap necessitating the need to "catch up" in the first place? They need a way to keep you subbed. Which, to be fair, would remain true even if we were overflowing with content. No developer can keep up with how quickly players complete content. Case in point, that 24 man likely took a month or two to fine tune and test yet will be over with in 40 minutes. For a subscription based game, there always needs to be some form of progression limitation.

Incorrect answer.

If the gear is the main motivator for doing this, there is nothing keeping you from unsubbing and returning when there is an echo and the tier is unlocked.

The main motivator is the fun and enjoying to the fullest what the new expansion/add-on has to offer.

Side note, you can already complete every piece of content out there with just the crafted gear that has been available and needs no tome farming nonsense. (well it does need some tomes but not near to what you need in order to be BiS)