PC-BSD and to a lesser extent DragonFlyBSD do that. But there's just not enough people willing to put the work in (and in fairness why should they?).

FWIW I found installing FreeBSD pretty straightforward as soon as they started supporting normal disk partitions. It's closer to Slackware than Ubuntu, but that's also the appeal of FreeBSD - it doesn't have a whole lot to offer someone who wants something automagic like Ubuntu IMO.