Parts of it are pretty inconvenient, like with iMessage and FaceTime not working normally, but aside from that it’s not noticeable for my use case.
Despite the inconveniences, unless animated emmojis are important to you I don’t know why you wouldn’t enable it given how strong its protections are.
But users who need a highly secure phone? It’s entirely possible to use the phone without media embeds in iMessage, or shared photo albums, or websites loading in 900 fonts. It’s a trade off likely worth making in some situations.
It’s mostly that I don’t want to be that guy that leaks my company’s secrets.