Those days are sadly long gone. There really is not an argument to make that the rule should be relaxed. Probably of the most ( or "few" depending on your perspective) common sense rules put in place after 9/11.

I have happy memories of spending an hour on the flightdeck of a CX A340 on a HKG to ZRH flight in March 2001. I've done the same on the following aircraft:

BA DC-10 JFK-LGW June 1993

BA 737-200 LGW-GVA June 1993

BA 747-200 LHR-JFK July 1993 (Captain was Stanley Stewart, a well know aviation author)

AZ MD-11 JFK-FCO June 1997

AZ 767-300ER MXP-JFK July 1997

FN 757-200 KEF-JFK December 2000

VS 747-200 JFK-LHR December 2000

SR MD-11 ZRH-HKG March 2001

AF 747-400 CDG-JFK June 2001

My real highlight was sitting in the jumpseat for landing at both LHR and ORD on a Virgin Atlantic A340 in August 2000.

Keep in mind that in-flight flightdeck visits were prohibited for U.S. carriers prior to 9/11.