It's perfectly simple. Let's recap:
When retirement was first introduced, the retiring requirements were higher after each generation, but the bonuses also increased with each retirement, making it all worth it. It didn't take long for it to become apparent that the WPF bonuses from retiring were unreasonable. To make up for their loss, the ramping requirements for retiring were removed.
Unfortunately, there was another oversight here -- the XP bonuses still grew faster with each generation. You (and a lot of other people) took advantage of this to retire many times over at an increasingly faster rate, to get more heirlooms and level faster.
Now XP bonuses for generations are stable, just like the requirements. Problem solved. You really shouldn't be complaining -- you've got an unfair advantage over newer players by virtue of having done many retirements back when it was easier.
Instead, be happy that your generation count or heirlooms haven't been reduced to compensate. Hey, with some luck, they still might be.