They served their purpose as a way to recognize themselves and then used it for the thematic and iconic moment so why wouldn't they discard them

They never forget vivi and they don't need an x to remind them of their future crew mate by that logic if they kept the marks does that mean the other crew mates like robin, franky, brook and jinbe would have the mark too? or we just see straw hats with an x and others who don't like some redundant seniority system

They weren't such a big deal to the crew I mean vivi probably discarded hers too

Lol they still remember their adventures. if u see vol. 90, luffy is like "oh, vivi! we havent seen her in a while!" and remember when sanji and chopper were cutting out the pieces of the princesses and kureha? this shows that they remember

Oh yeah

XD

You think they dont take showers ?

It was only for that moment I think. It's weirder if it was still on them. Not like they tattooed it on.

Hell Luffy remembered in impel down which is why he still held a grudge against croci until iva told him otherwise

It is erased when they get wet from rain.

That's probably not true. Luffy remembers everyone he meets, including Vivi. I'm guessing the X was on their wrist right? (it's been so long since I've seen those episodes) It's probably not showing their wrists in the other episodes because they have other interesting stuff to show rather then just their wrists.

And it prob faded after mroe than 2 years