In short the ability to aviate manually should be innate and not require all the full attention of the flying pilot. This will only be available to those that keep their scan and skills up to date.
Spot on. The tick in the box flying exercises often allowed in the sim every 3 years without any accompanying stresses come no-where near achieving the abilities you describe.
Something so simple is to practice is an ILS on the small SBY instruments. When I did my command upgrade it was an exercise in the syllabus. It was deemed that any self-respecting captain should be able to. Many of the new generation have full PFD on SBY electrics, and it would take multiple failures of electrics & screens to achieve the small SBY instruments only, but why not use it as an educating exercise to improve feel/touch & scan. You can do an OPC in quick short time and then use the rest of the 4.00hrs for pure manual flying exercises with a few simple QRH non-normals thrown in to tick those boxes. You keep flying under radar vectors and configure for the ILS while the PNF does the QRH switching under your supervision. It would teach PF AND PNF/PM to multi-task and be accurate. Just needs some imagination in writing the annual syllabus.