And, of course, #TNG S6E7 is one of a few of the episodes that are so fundamental to the whole story line and universe, yet so totally ignored by next episode. There are a few...
- The reason all aliens look human is revealed. S6E20
- When transporters can copy someone (Thomas Riker). S6E24
- And this one - when transporters can make someone young again. S6E7
These would destroy a lot of the whole universe / concept if explored.
@revk Season 2, Episode 7 - the transporter can cure basically all illness by filtering out pathogens and reversing genetic damage (coincidentally by curing Dr. Pulaski or rapid aging).