The complicating factor is this:
Few, if any of the major automation related accidents have been caused by a lack of "stick and rudder" skills. It is more nuanced than that. The major factor they have in common has been a failure to perceive an indirect mode change or understand a confusing system failure in time to prevent an accident. Being able to manually fly a decent raw data ILS, or fly an arc within half a mile is not really that relevant. In fact it is presumptuous to suggest that the incident pilots weren't as skilled at manual flight as any of us.
Some will argue that constantly practicing manual skills gives you a better ability to detect anomalies sooner. There may be some truth in this but you'd need to do it far more than is realistically practical and it introduces it's own set of risks which may outweigh the (debatable) rewards.