Well if you read each time to kill Oro you actually 'forget' everything. lol
But I'm not sure where I sit on this, I think not having access is fair enough, when you reset you agree to go back and start again with extra abilities, but lose everything else you had up to that point, including access to Hoshigakure.
But if reborns were given access straight off the bat I wouldn't complain.
And programming wise it isn't hard to make it that way, just have to change the condition of it appearing to, 'Kills >= current limit or resets > 0' from, just checking kills.