At cruise, a/p is at its most practical and important aspect. To select a/p only to sit on the edge of the seat and birddog every bump and discrepancy is to eliminate the need for it. On a sophisticated transport, autoflight is a form of commanded complacency. So its disconnect (uncommanded) of course comes at an inopportune moment. After a series of warnings, chimes, and an uncertainty in the F/D, one pilot needs to retrieve the checklists and troubleshoot, solo ? Yes, because the PF needs to update his scan, 'get' the panel and the 'feel' starting with Pitch and Power, from a degraded (of course) SA. The PNF is at an immediate disadvantage, all the alerts are after the fact (of course), and there are many. Both Pilots are behind the a/c. The a/p was behind enough to need to disconnect. No matter the reason, an unexpected a/p disconnect demonstrably causes problems, some of which seem to have gone unaddressed.