I don't know about "EA rationales", but rule utilitarianism is unpopular among philosophers largely because it's believed to collapse into act utilitarianism. The phil101 caricature is that rule utilitarianism says "no stealing, because 'no stealing' is a rule that increases utility" and act utilitarianism says "steal if you think it maximizes utility" - but on the one hand "no stealing, except for bread to feed your starving child" is an even better rule, and so on; and on the other hand not incorporating uncertainty into your decision procedure isn't being a good act utilitarian, it's just being an idiot. And so in practice they endorse the same decision procedures in pursuit of the same end.