I like high rise jeans well enough. As long as you pair it with a nice crisp top and shoes for a clean look. I got a lot of influence of the 'modern' clean look of the 80s through my Mom, and I definitely think it's a casual and slightly retro simple look.
It's not for everyone, just like the ultra low-rise doesn't suit everyone either, but I think it can be very nice. Lol, besides, there's no way your underwear would show.
I think the versions on Gwen & the 2 models look great b/c these women have really slim hips and can pull off this look. They're also wearing fabrics other than denim, which I think makes a world of difference. As for the denim versions, they are just ridiculous on anyone, regardless of body type. Geez, is there any trend Mischa doesn't follow - she looks like a fookin' idiot.