I Like The PBE Changes To BotRK Overall, Yet I Think It Should Keep The Base Damage From Cutlass
It's not a lot I know, only 100 base damage, yet I think it would be more appropriate than losing out on it completely when BotRK is finished as an item.
It's the same with Guinsoo's before its buff, when you would lose out on the base attack speed you got from the Recurve Bow upon finishing the item, though not nearly as problematic.