Tom
Istar
When Aragorn marches helmless on the black gate, nobody cares. When Nightwing, Green Arrow, Conan, Rambo and more fight with vital parts exposed nobody cares. These characters are no more or less practical than the sexualized female ones. The difference is that their impracticality is used to convey more than sex appeal, they typically communicate strength and authority. The sexualized portrayal is not in itself a problem, the imbalance is. But that reflects the standards in all of western culture.
In Aragorn's case it's not a show of power but instead an old and very common filmmakers' trick. Helmets obscure the face and make it hard to read the expression, which is essential to a character's connection to the audience in a highly visual media like film. So the character either goes into battle helmet-free or loses it sometime during the fight, usually before a key moment involving a lot of emotion. An example of this would be Eowyn removing her helmet before killing the Witch-King--this not only reveals her gender, but also clears our view of her face so we can see her expression when she kills him.
The rest of these are male power fantasies. They're meant to serve as a self-insert for the men watching them. There's a big difference between a male character created by a man for other men to see themselves as, and a female character created by a man for other men to see as a sexual object.