JFK's tax cuts came in in the '60s, but didn't really go all that far.
Taxes went up in the '60s ( another halcyon time, according to some here ), but it wasn't until Reagan, in the '80s, that there was any tue tax reform/tax cuts.
BTW, the tax level ( where the cap on wages for FICA ) went up in the '60s.
You say the TOP LEVEL income tax rates were very much higher in the 50's...but what about for the average family income? I read that the figures were low enough that a single wage earner could provide support for the family, enabling the wife to stay at home with the kids, which is the lifestyle that most of us in the 50's experienced.