I think Grado does improve its technology.....albeit at a pace of a snail lol.
This is how I see it: 20 years ago....they came out with the HP1000 all aluminium, but very heavy and very expensive at $595 which is crazy prices back in the late 80s early 90s. But the sound was too boring.
So they release the cheap plastic ones to bring to the mass market, and changed the sound to make it more musical and exciting. That's progress.
Then they went with wood for the RS1 & RS2, which improved the sound significantly from the plastic one. Another progress.
Then in the late 90s, they released the bowl pads which replaced the flat pads. This improved soundstage a little bit and gives a nice dose of airiness to the sound. Progress no#3
In 2006 they changed the sound completely with the GS1000 and gave us the bagel pads. Progress #4.
In 2009, they decided to bond wood and aluminium together for the PS1000 and HF2. Progress #5.