The decision should be left to us, the players. Let us decide whether we want to start fresh, or continue playing as our current Guardians. The best thing they could do is add 3 new character slots, plus 3 new Class with 3 new Subclasses each. It would encourage players to try something new while still giving us the option to go back and continue our Destiny 2 adventure as our Destiny 1 Guardians at any time.