This is ignoring that a huge part of religion hasn't been about the actual worship, belief, and so on, but instead about binding a group into a cohesive whole.

The punishment for leaving that whole is necessary, otherwise people would leave when it benefited them.

People, by my observation, rarely follow any religion because of absolute faith, trust, and so on. They follow religion for support, community, and a sense of belonging. Leaving that is a small pinprick in the sides of everyone who was part of that group, who just essentially lost a fraction of their sum power, the total human-machine-type capability to think, to support one another, and so on.

The church used to go hand in hand with the government, it was the thing that bound us all together, after all, the crown was a god given right, the power to lead. We are sitting in a modern world where that group-cohesion has mostly fallen apart, a world full of individualism, of interconnection created by networks of small relations rather than dedication to some ideal of a larger whole.

It's from this perspective that we can say that it's silly to have things like apostasy, because it really is a silly notion from an age where machine labor accomplishes far more than human labor, and where all our needs are easily met by connections made outside of the church, be it in the government's support for the poor, or the media's capability of connecting us.

I think this is the source of all the issues with religion today, we are looking at a system designed to create and hold together communities that existed in eras where our day to day lives would make us look like gods in comparison, and trying to use it to suit our modern needs/ideals like comfort or "good" morality, rather than the purpose for which they were intended.