But I think there's a virtue in those later seasons.
In real life, characters come and go. Sometimes they guest star but never make it to the regular cast. Sometimes they're absent for a few episodes and it leaves you wondering why. But life continues. The original premise has shifted, but at its heart, your life is still the same show.
Later seasons have a freedom. They're free from the formula of what they were. Even when that formula was for something amazing, the freedom to do something new and different is exciting. Kind of like how I get nostalgia for everything that's happened to me, but I keep doing new things I've never done.
TV shows are friends. You love them like people. You love all of them.
Like Abed said in the series finale of Community:
"TV defeats its own purpose when it's pushing an agenda, or trying to defeat other TV, or being proud or ashamed of itself for existing. It's TV; it's comfort.
"It's a friend you've known so well, and for so long you just let it be with you. And it needs to be okay for it to have a bad day or phone in a day.
"And it needs to be okay for it to get on a boat with Levar Burton and never come back. Because eventually, it all will."