[zaarn]

Cartering to power users isn't usually good for marketshare because it means you limit your market share to a small subset of the market. Making Thunderbird more accessible and making GPG more accessible, even if that means you can't support some niche use cases, is usually the better choice.

[t0astbread]

For a mass-market client, yes. But in an ideal world there would be alternatives that don't aim for market domination catered to a more advanced user base. Those could include functionality that would be unsafe for users who don't know exactly how it works.

[zaarn]

Well, that is what extensions are for in Thunderbird. As long as atleast one poweruser is willing, they can write the powertools.