It's more than just stupidity or malicious stupidity. While these are serious flaws that Musashi has to overcome, this is just her secondary flaws, her real flaws, and one that aggravates Musashi's secondary flaws is her conceited and arrogant nature. She is quite literally the most vain and arrogant shipgirl in this story, which is an irony, because her real life combat record is a worthless roll of toilet paper.
Her arrogance and conceit is driving to gain attention wherever she can even if it's supremely detrimental to others. I for one cannot wait for an event that destroys her tough girl act.