Braces of various designs are commonly used for women's cycling shorts but none have really taken off as "the best thing" as you can see from the range of variations and the number of women who still wear non-bib shorts. I'd be interested to hear the views of some of the women who spend a large part of the day in the saddle on their choice of shorts.
IME:
Anything that involves significant undressing and dangling straps in a toilet bowl to have a wee is a major disadvantage. Doubly so if you have to do it in the wild.
Waistbands don't seem to cause me discomfort, though they're often looser than they should be.
Clothing that doesn't fit very well is normal and ordinary and just a part of the way the world works. Most of my trousers have several inches of spare waist in order to fit properly in the arse and thighs, so it seems likely that cycling shorts are similarly affected.
I endeavour not to spend longer than necessary in the saddle
[1], therefore my choice of cycling clothing is influenced by what also works well on a seat (that's mostly about pads that don't rub your inner thighs, and minimising lumpy bits down the middle of your back).
Jersey waistbands riding up is an issue, particularly with 'unisex' designs, or anything that's oversized because women's cycling stuff is designed for people without shoulders/boobs. Mostly harmless with a saddle, and can be mitigated by carrying things in the pockets. With a seat you end up lying on the bunch, so it needs regular straightening. My latest discovery is a recumbent-specific women's jersey which miraculously manages to put the waistband in the right place and stay there.
So while the idea of attaching jerseys to shorts (in a non-lumpy way) has some appeal, I don't see the point in bibs.
TBH, the cycling clothing innovation I'd like most would be humvees with room for quads.
[1] The 'best bike for the job' principle means I mostly use saddles for utility rides and off-roading, where (once nasty seams have been eliminated) durability and convenience of clothing are more important than long-term comfort.
