I know two women who have tried those. In both cases they tried for several months to get used to them, but they gave up eventually because they're so unpleasant to use, and it never gets any easier. Apparently.
There are women who find that menstrual cups aren't for them, but in my experience, they tend to be the exception. Using one myself, and having turned many of my friends onto them, they're generally hailed as the greatest thing ever invented around here. Not to say theres anything wrong with your friends, because everyone likes what they likes, just wanted to throw my own experience.
Using one myself and best thing I've ever tried! Takes some practice but once you got the hang of it it works great. But think it's different from woman to woman!
I feel like most of the university-educated young women I know use Diva Cups or Keepers (and many don't mind talking about them and promoting them to others or I wouldn't know that). I think their usage really depends on local culture, social norms, propensity to shop in organic grocery stores where they are often sold, etc.. The first women I knew who used them started in the early nineties.