I think time has alot to do with it as well. Some good points were made here. Our ears have evolved over the years to the point that their much more refined and detailed compared to years ago.
I remember listening to a pair of JL Audio 10W6 in a custom bandpass box being run off a Phoenix Gold M50 in a Blazer back in 95/96 thinking that was the loudest cleanest bass I had ever heard.
Sub tech has improved so much over the pass few years that you def get more for you money IMO. Rockford Fosgate Power 1000 was there biggest amp and ran a pretty penny brand new. You can get a amp with similar output for a fraction of the cost.
Doesnt mean the older stuff is bad, just a little outdated with modern times.
My late cousin had a 1993 Suburban with (6) Fosgate He2 15" being powered by a pair of Fosgate 800.2 running bridged at 2.66 ohms each and it was crazy in the truck. Subs were sealed in a "V" shaped enclosure from the second row back to the tailgate firing up (no wall). Earlier this year, I had a Orion 8002 running my front stage, just to give you an idea of how much times have changed and how power has gone up.