I think being tough in a skirt keeps the feminism feminine. I think a strong (physically or otherwise) female character doesn't need to wear a manly outfit. I think that hurts feminism if women are expected to dress like men or deny their femininity to appear "equal."
And as you pointed out, He-Man wasn't wearing pants. Or more to the point, it's not like we have fully armored men and chain mail bikinis. Both genders show skin, and the outfits (male or female) don't come off as gratuitously revealing.