I also don't like the absence of the Girdle of Masculinity/Femininity. It is a D&D classic and a lot of fun. And if you think about it, it might actually be a quest objective for characters that actually want the change.
For a long time I really despised the gender-swap curses on items because the gender you belong to is not a curse (though society can certainly be extremely unfriendly to you based on your gender if the campaign includes anything approaching realistic sexism and misogyny/misandry). Rather recently however, I actually asked myself why I hate these cursed items, and this is what I realized:
I do not hate the items because they treat changing genders as a curse; I hate them because they are poorly played out, frequently by adolescent gamers (or puerile adult gamers) who focus too much on physical characteristics and gender stereotypes.
In every game where I've seen a PC afflicted with a gender-changing curse, the DM (and, often, other players) has tried to tell the player how to act more like the gender they have been changed to, claiming that their mindset, motivations, sexuality, and emotional state have been altered by their gender change.
This does such items a HUGE disservice.
Having your gender changed is not a curse if you also change in your mindset, motivations, emotional state, etc. You have effectively just changed your gender with the PC having no real issue with it, while the player probably does. But, if the item just changes the character's sex (or just changes the character's gender identity), then the character is left with a very real conflict between who they are and their physical characteristics. In real people, this conflict leads to depression, self-mutilation, and suicide, and that sounds an awful lot like someone laboring under a curse to me.
So, I have changed my stance on sex-changing curses, and items that inflict such a curse. If handled with actual tact and maturity, they can lead to an enormous amount of RP opportunities, and they may even help people learn to have empathy for those people who are really suffering from a gender/sex conflict.