In the brachos we say every morning, men thank God for "not making them a woman" (and women thank God for "creating them according to their needs").
Why don't both men and women just thank God for making them the gender that they are? Why do men thank God for not making them women, as opposed to thanking God for making them men? Further, why do women have an entirely separate bracha? Why don't they thank God for making them women?
If you look into the morning brachos (prayes) it first says:
1) Thanks for not making me gentile. 2) Thanks for not making servant. 3) Thanks for not making me woman (for men).
So it is progressive statement of what the person is not.
That is because a Jewish man has much more obligations towards God than a Jewish woman. Both have much more obligations than a servant of a Jewish owner. And finally this one has more obligations than a gentile.
This statements manifest the eagerness to be obliged to serve God. The more, the better.
I am basing this off of a tape I heard from R' Dovid Orlofsky - he did not cite his source, but a close student of his told me that a lot of what he says is from HaRav Moshe Shapiro.
If we would say "thank you for making me a Jew" in the positive, it would put a certain focus on us as filling that role, as if we were living up to everything that that demanded of us. Similarly with being free and being male, we would be highlighting our occupation of that role and creating an accusation against ourselves if we do not live up to the responsibility demanded by that role. However, we do want to acknowledge that we are thankful to have been given the opportunity to have more responsibilities. Therefore, we say it as a negation of the opposite, in order not to make a direct declaration that "I am a free person."
This is also why women make a different blessing, as in other answers given here - we are thanking for the higher responsibility that we have.
The Brachos of "shLo asani Goy, Eved, and Ishah " are one group and we are thanking Hashem for obligating us in Mitzvot as each one has more obligations than the other. It has nothing to do with thanking Hashem for creating them the gender they were born as. So the bracha is "Thank you Hashem for making me obligated in even time bound Mitzvot" and not "Thank you Hashem for making me the male gender"
As sam alludes, the Talmud (Eruvin 13b) concludes that it is better for a person if he was not created.
Therefore, the sages did not want to establish a blessing thanking Hashem for creating a person, so it is phrased in the negative. Even though we say a blessing on bad things just as much as positive (Mishna Brachos 9:5), however here the point is to thank for something positive.*
Regarding the Bracha that women make, this is indeed like accepting Hashem's judgement, but that was added later. Some communities don't say it at all.
* I have definitely seen that somewhere, but I'm not sure where.
"One must make the blessings 'that I was not made a Non-Jew', 'that I was not made a slave', and 'that I was not made a woman', for each one has an additional praise. First one says 'that I was not made a Non-Jew' who is not obligated in the commandments at all, and after that '...slave' who is obligated in some commandments, and after that '...woman' who is of Jewish lineage and obligated in all the commandments. Therefore the blessings must be said in order. If one said 'that I was not made a slave' first, one would not go on to say 'that I was not made a Non-Jew', and if one said 'that I was not made a woman' first, one would not go on to say 'that I was not made a slave' or 'that I was not made a Non-Jew', because 'two hundred includes one hundred', so since one already made a blessing on the greater thing, the lesser was already implied." -Chayei Adam 8:2
If we made blessings thanking G-d for making us men or women, we would only be able to say the one blessing instead of three.
I've heard that if you were to say: "thanks G-d, you made me a man!" would imply "now I'm a man! -- i.e. dignified, important, everything I'm supposed to be -- and many/most of us aren't there yet.
G-d says that He intends to create humanity in His likeness. The Sforno says that it's up to us to determine how G-d-like we will be.
