@sanji''s_dad:
The ancient weapons are no joke the world govt is able to control the entire world and they only have one of them in their holy land and crocodile thought he could take the over world with just one of them but he did not know that roger moved it to raftel plus the mermaid princess controlling the super sea kings is no joke either since the main method of transport is by sea!
The straw hats can replace any crew members skill they bring to the crew sure they might not be as strong as the person they're replacing but you can find another cook if they need even luffy was hunting and eating his own food as a little kid sanji just makes the food last longerand taste better however Robin is the only living person able to read them THE ONLY PERSON understand? they cannot replace her since no one there to replace her with!
her home island was wiped out if she dies or gets captured and she never tells them anything then they will never know anything then they owned by the 3 ancient weapons and the world govt takes over the rest of the world by taking over the new world!
Roger did it without the need of an Oharan. Luffy can do the same.
Robin is not replaceable, but that's not because she's the only Oharan survivor, but because she's a crewmate. They have no interest in using her abilities to get weapons. She has no interest in that. Luffy has no interest in that either.
Same for Shirahoshi. Luffy will save her because she's a friend, not because she's a weapon. Do you really think Robin saying that she's Poseidon would change anything? The Straw Hats couldn't care less for that and would try to save her anyway.
You're acting like the Straw Hats only value Shirahoshi as a weapon, and not as a person. Same for Robin. The Straw Hats literally have no reason to go after the weapons. Robin could literally lose her ability to read poneglyphs, and the Straw Hats wouldn't care.
Oh, and the WG is trying to prevent Robin from awakening the weapons. If anything, the threat of weapons being used only exists because she exists. If she actually died like you say, the world would actually be safer too. This is pretty much one of the main points of Enies Lobby and it actually destroys your entire argument.
Never mind that Luffy already has Shirahoshi at his side, and Robin was not important for that. Luffy himself became friends with one of the strongest beings in the world without Robin's help. And if Shirahoshi gets captured, Robin will not change things either, as the Straw Hats will go after her anyway. Essentially, Luffy unawarely "obtained a weapon" without needing Robin's skill. That's just how "useless" her skill is to the crew.
Heck, I can already see it. Robin tells the true history and everybody in the crew would fall asleep listening to it. They don't care about exposition that does not benefit them in anyway. Robin is the one who wants to learn history, not them. Her skill just there for metafictional purposes.
One could argue that you're pretty much missing the point of Robin's dreams and motivations by having her tell the Straw Hats about the weapons.
Oh, and don't make stuff up. There's nothing saying that Roger moved Pluton around.