I don't know. Just keep your account and leave everything the way it is? Also, don't listen to those, "Can I have your stuff" comments.

Go on hiatus, but keep your characters. Return when there are truly new weapons to try, new monsters to beat up, new bosses to vanquish, etc.

As far as I can tell from the people I know, this is how many veteran players handle this game. They enjoy each brief return, because it reminds them of whatever they found delightful: the art, the devilite humor, the weapon mechanics, the friends, etc.

Well the problem is that everything revolves around the dollar. OOO answers to SEGA and has to meet a bottom line for them.
I find that while the drop rates of orbs are fairly low, if you find the right arcade gates you will have a great chance of getting what you need. If there are arenas in stratum four, I will grind there for a while because I can get elite orbs quickly. Eternal orbs aren't a concern for me since I already have too many.

Prize boxes being purchasable alone is what they did to stabilize the market. Back when you got energy with the prize boxes the promotions would cause massive fluctuations in the market, and I believe it made them a bit less special. Now when promotions come around, prize boxes only instead of with energy helps preserve the market unless the promotion is in insanely high demand, like the Rose Regalia one we just had. Energy took a sharp rise during the event because the items are that high in demand.

The promotions help OOO meet their bottom line to SEGA and give their employees salary. In addition, the promotions are mainly work for the art team, which takes no time away from the coders trying to fix/update the game.

I can't make you NOT feel that way, but here's a TL;DR of what I said.

1: All games revolve around the dollar. This game does it with cosmetics, which I feel is a respectable way.
2: Crafting materials have a low drop rate, but remember that the cost of buying orbs is exactly identical to the crafting costs before there were orbs.
3: To find the crafting materials more easily, have a look through the Arcade.
4: Separating boxes from energy stabilizes the energy market. For the first time in 18 months, in July, I had seen the CR/CE trade ratio at about 6500CR per 100CE.
5: You aren't required to buy the boxes. You said they contain a cosmetic item that has little impact, but some people are costume builders (like me) where it has a big impact for them.
6: Promotions are planned ahead of time, and the Rage promotion actually had content planned to come with it, but the content had to be delayed for whatever reason.

I'm on a hiatus basically until actual content is added in the game, I, like you, have done everything there is to see and do, and when you've done them more than a 100 times, it gets boring and repetitive, what I did is find a game that grabs your interest and can hold you for the time being until OOO releases actual content, no, promos don't count now get that out of your head, OOO will see my money when ACTUAL content is in. Content is permanent, not event, reskins, or anything you've done in the game more than 20 times.

Believe in the Bipitty-Bobbity-[Bopp]
:P