This is them p much every post ts arc except WCI which was personal for Sanji. They're always just helping the friends they made along the way.
I can see what you mean, but at least they had some sort of goal to work towards every time. In Egghead they just went there because it looked fun, and ever since then they've just been strung along for no real reason.
Oda makes it seem like the Straw Hats get invested by having e.g. Luffy and Sanji making the classic "I'll help/save you" promises to people, but this time around those promises aren't even kept, and they don't even seem to care about it immediately after. The story doesn't even care, in fact it seems to treat it as a good thing because now Vegapunk gets to spread his message to the world.
And aside from that, we've gotten reactions to Vegapunk's message from every side character/antagonist/etc. under the sun, but the Straw Hats aren't even engaging with it at all. I don't get why Oda is writing the Straw Hats to be so indifferent about the history of the world - aside from Robin, even though she barely had any reaction so far either - when that is what should be driving them to Laugh Tale, and whatever needs to be done there. It feels off to me.