Give it time I would say. Nobody cares about not having a central mail index, because everyone is used to how email works.
Now with Lemmy we are changing the central approach of reddit to a decentralized one like email. It’s not a big problem if you ask me, it’s only that people don’t like change. Still, I think it’s crucial that we stay with the decentralized approach instead of creating the same problems we had with reddit/facebook/twitter and the likes.
We did it the wrong way nummerous times. This time, let’s be patient and please do it the right way for once.
And don’t forget that the big corporations are already trying to undermine the new approach. Look at meta and threads for example.