Your statement here makes zero sense. When players have put in dozens or hundreds of rolls into a mod, and none of that work is converted into new Grade 5 system where the new mods are massively more powerful, why would a player ever be "happy with what they already have" when FD devalued all of that hard work?
I was restating your own complaint so if it "makes zero sense" that's on you.
It seems like what you're actually complaining about is that better mod's are now available, thus relegating the mod's people spent a lot of effort creating to mediocrity.
Well, boo-hoo.
Things change.
I've got plenty of ships which I've spent a lot of time and effort modding.
I'm looking forward to 3.0 so I can upgrade those ships even further.
I already put dozens of hours into the mod's so I'm not at all bothered about putting in even more time to improve those ships even more.
What you're doing is like moaning that it took you 2 years to build a Vauxhall Viva by hand and now a machine can build a Vauxhall Astra VXR in half an hour.