I can't imagine developing any software that involves relationships between entities that does not have data consistency. Check constraints, foreign keys, and data type validation all provide a minimum sanity level of the underlying data that allows your mind to focus on more important things. Otherwise you're entire application is going to be littered with those same sanity checks.

I'm not saying that all apps need that type of data store or that there isn't room in this world for NoSQL stores, I mean specifically that complicated interdependencies and validation checks lend themselves well to the relational model.

The client will never experience Committed unless it really is committed, and thus never report that it was successful to the user.

At the very least I'd want to know exactly how much data loss we are talking about, which is probably harder to answer than just using a platform that doesn't suffer data loss in the first place.