This proposal comes from the right wing philosophy of "hit 'em hard and hit 'em long" school of justice which believes that persuading citizens to confirm to social acceptable behaviour is best brought about by the implementation of hard hitting punitive measures no matter the context. The "lock 'em up forever", "three strikes and you are out", and most extreme, the death penalty lobby all fall into that category, none of which have ever either reduced crime or changed behaviours.
The irony is however, that I think MacAskill is trying to do something creative here, which is get parents to take more responsibility for their children which is something I would support. but eh is limited by a dearth of imagination amongst those who aer advising him, and more importantly, a large right wing support base to appease but also the left wing groups who took their anti Labour perspective to the SNP after the SSP imploded following Tommy Sheridan's demise. So we end up with the worst of both worlds; more punative sentences but no real support or help for parents to take that responsility.