As much as a steeper regression will hurt once it kicks in, I can absolutely see good reason to toughen the penalties. I was off to a late start, but even with high activity from my 2nd season onward, I'll probably be playing 12-16 seasons with the current system provided I keep earning TPE at the same rate. That's good for my player, but not for the league.
Another major factor with regression is that it may cause players to lose interest. Many will just retire and start a new player once it kicks in as the thrill of becoming better every week goes away. However, others may force themselves to stay out of loyalty to their team even if it causes them to enjoy the league less. The slow decline could potentially cause them to lose interest over time. At least with a punishing system, it will make the message clear that it's time for new players to shine and encourage users to try out a new players, which makes the experience fresh for them once again.
Another major factor with regression is that it may cause players to lose interest. Many will just retire and start a new player once it kicks in as the thrill of becoming better every week goes away. However, others may force themselves to stay out of loyalty to their team even if it causes them to enjoy the league less. The slow decline could potentially cause them to lose interest over time. At least with a punishing system, it will make the message clear that it's time for new players to shine and encourage users to try out a new players, which makes the experience fresh for them once again.