Japan is still mostly set in the traditional roles - the man being the fighter (so to speak) and the woman being the caretaker.
Now, Naruto is a shinobi world and the main character is male. Of course some male characters will be powered up more, simply because the focus lays on them more than on the others.
That doesn't mean the female cast is useless or weak. They each have their own strength.
We have Tsunade and Mei who are Kages - and considering one of the qualities a Kage needs to have is strength so they can defend their village, it should be clear that these two women aren't weak - and Tsunade is considered one of the best medic nins. So they aren't weak or useless.
Tenten is based on the traditional image of the ninja - only fighting with weapons and none of the fancy jutsu others use. She can be deadly with her weapons, so she isn't useless.
Hinata is part of the Hyuuga clan and I should think that she proved herself during the war that she isn't useless or weak. She got Naruto back to fighting again to give an example and she has been shown fighting during the war.
Ino was part of the plan and had to use her mind controlling jutsu. Again not really useless, despite the fact that she barely gets any screentime.
Konan was part of the Akatsuki and I think we can safely say that she was very strong as well.
Kushina managed to survive the extraction of the Kyuubi and she didn't seem the type to give up quickly.
Now Sakura. I dislike her and clearly am not a fan of her, but she isn't that useless. She's a great medic nin and obviously has a future in that field. Hell, she even managed to create an antidote for Sasori's poison which nobody was able to do. And her strength was necessary to be able to defeat Sasori (yes, she had help, but her brute strength was needed in the fight).
So all in all, the female cast isn't useless or weak. But most of them seem to focus themselves in the medical field, which isn't stupid. Without someone able to heal the others, many shinobi would have died. Look at Tsunade - without her healing abilities, the Kages would have fallen sooner and even now, cut in half, she seems to have a plan.
You also have to take into consideration the Japanese culture regarding the roles of men and women. You can't compare it to the Western view, because there are obviously differences (though in Japan women aren't confined to being a housewife anymore and have started to work as well).
So, while indeed some male characters are very powerful, because they get the most attention in this manga, that doesn't mean that most female characters are weak. They are either fighters as well like Mei and Konan or are more experienced in the medical field like Sakura and Tsunade. Does being a medical ninja make them weak? No, it doesn't. It makes them useful in another area than fighting.