Heck, there have been many cures for death that got ignored because they would've changed the status quo too much. Transporters can reverse aging, and should be able to heal injuries as well. (Beam an injured person directly to sickbay? Okay, why not just tweak the transporter pattern so they materialize without the injury? Then you wouldn't even need sickbay.) DS9's first season gave us a trifecta: quick-cloning in "A Man Alone," the ability to download one's mind into a new body in "The Passenger," and death-repairing nanotech in "Battle Lines." Among the three of those, death could've been conquered altogether. The Federation should've already had immortality and the fountain of youth long before they discovered the Ba'ku's magic ring radiation.