I think we as tax preparers should ask our clients what they want to do, after explaining to them that IRS may not get around to doing this until late summer for MFJ returns, and might not get it right even then (especially in community-property states).  Another factor is whether it's any more work, if a state amended return must be filed.  

One size does not necessarily fit all.  And we work for our clients, not for IRS.