The new model bats were already out and so would have been sent back unsold. This allowed bat manu's to go ahead and sell the inventory that was already out there and then make the money next year when everyone is forced to buy new bats. Granted there are many that have not bought a new bat but there was a huge amount of people whose sons were using composite (I am one) who had to buy an interim bat and now will have to purchase another bat next year. Couple that with the folks who simply had to replace a worn out bat this year and again, same situation, they are buying two bats. Had the rule gone into effect this year I, and everyone else who bought a new bat this year for whatever reason, would have simply bought a new BBCOR and been done with it...
They were already going to profit off the sale of the new BBCOR bats anyway but they stood to lose a ton of money on the non-BBCOR inventory sitting in the warehouse had the new rules gone into effect this year...