It's well-known in golf swing how previously good and effective technique from even the very best pros can quite suddenly, or more gradually, deteriorate. From either new mental pressures or very subtle changes in bio-mechanical stance and mobility. The original good swing technique then has to be re-built or re-learnt - that's why pro golfers spend heaps on highly specialised swing and bio-mechanical coaches.
Bio-mechanically, rugby kicking when closely analysed has similar attributes of stance, weight distribution, mental factors, balanced body strength, arc angle and so on. Successful kicking from hand and tee requires immense practice and the very best kickers almost always use specialist kicking coaches more or less continuously as it's known to be not just a 'self-managing' type of skill set - witness Wilkinson and Dave Alred. Why would a Wilkinson so attach himself to an Alred if such coaching skills were 'not really necessary'.
I have no doubt whatsoever that someone like Stu Lierich (
https://kickcoaching.com.au/about/) or Mick Byre could, if retained by the ARU full-time to drive a national, all-season-long kicking skills support group, improve Australia's elite rugby kicking skills immeasurably.
We have many players who can kick well - Foley is a proven example - they are just not consistent enough or varied enough in their skills or they lack adequate distance. They may also have underdeveloped mental techniques to deal with varying pressure situations (I suspect that mental factors may have underpinned Foley's first-off penalty hand kick problems in T2 and T3).