[kevb]

If we ignore the word "user" it feels (and is) a lot less like abuse and actually fits very well. Linux has a proven and secure method of isolating access, and on linux servers and linux on the desktop this is used by different users to protect them from each other (intentional or accidental). In Android it's more important to isolate access between apps, again protecting them from each other, intentional or accidental. Even for well intentioned apps, like Chrome or Flash, that kind of secure isolation is extremely desirable, and I don't see much value in a custom built sandbox over reusing the isolation that's already proven.