I can't speak for youth Hockey, which would be most similar to lacrosse as far as early recruiting/prep school imvolvment, is it grade based or age based? But generally speaking in baseball & basketball, while there are reclassified kids playing, it is age based, and if you want to be 'noticed' or taken serious by D1 schools you have to play up 1-2 years. When did lacrosse go so off the rails that parents and players think playing down is the way to go? I get that it's the current system, and pretty soon most elite teams will be one re-classified team playing against another....not sure how that will play out in the future for the growth of the game among public school players.
The difference between baseball/basketball and lacrosse is that there is nothing beyond college for lax players (nothing really compelling at least).
This motivates families to position their kids in the best way possible for their college careers.
One's views on this situation probably most closely align with the combination of aspirations and physical maturation of one's kid.
For example, those who can dominate by playing down but are 'just a guy' while playing at the 'correct' grade level and have aspirations to play at a competitive college level are incentivized to play down.
To me, playing down would be humiliating. Using the logic that 'everyone is doing it' would hold very little water. However for many others, humility is simply not something they possess.