As far as the “breeding programme” questions, this is reflective of normal “market” shift.
Left-footed players were in high demand for some time because of a number of reasons—more on others below—but one of them was there were simply fewer decent ones available (as most people are naturally right-footed), which meant the ones that were got more chances to play/impress, in many cases preferential development and, if they were good enough, ultimately higher wages. So many parents, coaches, and agents began to prioritise developing their sons, players, and clients who are left-footed (and/or literally took right-footed players early on and turned them in the left-footed players; I actually know two players at the U18 level now whose dads did that when they were still in primary school).
Eventually you get a saturation, and the supply levels off.
That’s not to say there are actually enough left-footed players at every position for the top level of football right now, but there are definitely far more than there were even 10 years ago. The market is still fighting natural biological tendencies.
As far as why we look at a lot of left-footed players, there are tactical and mechanical benefits to having left-footed players, even beyond those specialised to left-sided positions.
This is a decent overview of them (just ignore the use of “soccer”).
Is there an advantage to being a left footed soccer player? Maybe. Learn the pros and cons of left footed soccer players!
soccernovo.com