There would have to be some limitations on actions of this nature; otherwise all away team deaths would be eminently reversible.
Marla Aster dies in "The Bonding"? Just generate a new Marla from the bio matter of her corpse, using the stored pattern. She only loses the memory of the mission, and Jeremy never knows he was technically an orphan for 47 seconds. Armus randomly murders Tasha Yar? Use her pattern to undo it. In "Legacy", either Tasha knows her sister well enough to detect her deception, or Ishara is so happy to see her sister that she joins them for real. And if you don't need specific biomatter, you could even generate a replacement Sito Jaxa. Sorry, Ensign Lavelle, that promotion isn't a lock after all.
Marla Aster dies in "The Bonding"? Just generate a new Marla from the bio matter of her corpse, using the stored pattern. She only loses the memory of the mission, and Jeremy never knows he was technically an orphan for 47 seconds. Armus randomly murders Tasha Yar? Use her pattern to undo it. In "Legacy", either Tasha knows her sister well enough to detect her deception, or Ishara is so happy to see her sister that she joins them for real. And if you don't need specific biomatter, you could even generate a replacement Sito Jaxa. Sorry, Ensign Lavelle, that promotion isn't a lock after all.