Why do we have seemingly odd currency caps in game?

[KDSilver]

Probably to limit purchasing power.

If you could save up 20k poetics, thatd be huge for buying old gear, etc. Poetics are used for a lot of things and they probably don't want people to be able to blow through things.

Same with previous tomes tones, and buying mats for crafted gear

What's the difference between actively bying anything each time you have 2k poetics VS actively bying when you reach 20k ?
If you're interested in spending your tomestone each time you cap, 2k or 20k, you'll just get more item at once with 20k but that's pretty much it.

[Iscah]

What's the difference between actively bying anything each time you have 2k poetics VS actively bying when you reach 20k ?
If you're interested in spending your tomestone each time you cap, 2k or 20k, you'll just get more item at once with 20k but that's pretty much it.

It does affect how quickly you can gear up once you hit a new endgame phase – eg. completing Stormblood and gaining access to the level 70 vendors. As you approach the end of Stormblood (around MSQ 68-70) you've long outgrown anything that the level 60 vendor can offer but you can't spend it on 70 gear yet, so you have to wait and save up. And I don't think you can buy a full set of gear with 2000 poetics when you get there.

(Making the vendors available at 68 like Idyllshire is available at 58 would help, but that's a separate issue again.)