Yes and everybody in star wars looks normal and like a natural person you’d see who didn’t do anything to alter their own appearance!
People in Star Wars generally look normal for their contextual environment. Holdo is on a Resistance capital ship fleeing the First Order. She’s not on Canto Bight. And no other human in Star Wars canon bothers to dye their hair wild colors. Why she would dye her hair purple as well as pile her hair into that crazy hairspray-intensive hairdo, while in the circumstance she faces makes no sense.
Recoloring her hair to a normal shade would make her more believable in such a serious situation.
If she were just another commander, would we have bought Poe becoming mutinous?
That’s on Poe, not Holdo. Poe is trigger happy and has problems answering to anyone but himself. He didn’t obey Leia’s orders either to stand down from calling in the bombing run, so it’s not about Holdo. Poe complains about them not telling him the plan, but he doesn’t need to know the reasoning behind orders in order to follow them. That’s not how the military works. Plus, if you read the novelization, Leia discusses with Poe on the shuttle that they were purposefully trying to tell as few people as necessary. Poe does what he wants, including that he likely wouldn’t keep his mouth shut if he didn’t think it necessary.
That’s why he’s a good pilot but a bad commander.