I believe the concern about disclosure is that the very foundation of every society on earth would melt into chaos if it was proved aliens have visited earth...in space ships...and we have bodies...and ships.
Your view was the one held by the old Brookings study in 1960:
More detail:
https://en.wikipedia.org/wiki/Brookings_Report
Imho that is why the elites began a gradual “disclosure” effort through entertainment to prepare the peons for what was to eventually come.
At this point most folks can probably handle it—but there will be some wacky cults and other weird stuff for a small percentage of the population.