Its not so much about the boobs as its about the fact she has a gigantic inferiority complex that she hides by trying to be the best ( explorer and otherwise ).
And yeah, Wendy really do need em.... IIRC back in the novel the reason he invented this was because wendy had back pain one day from working out or something.
So yes she 100% the reason this was invented.
Edit: this is addressed with a single text bubble in the next chapter btw
LMAOOOO Now time to look for the raws if that censored part was like that at the beginning. If it was, the fuck the mist... Mist = nightingale. Fuck mist = fuck nightingale