What could possibly go wrong?
This is supposed to make me feel better, yes? Because the developers writing those "prepackaged pieces" are perfect, and there won't be any exploitable bugs?
Maybe it's because I'm not a developer and people tend to fear things they don't understand, but to me this sounds like a terrible idea.
Also, it's probably gonna make e-mails even more annoying than they already are. HTML email reborn, as Google brings AMP to your inbox
With AMP embeds, email can now contain rich interactivity, not just text and pictures.