> Your worst case scernaio is so mild: nothing lost.

Not really. With Let's Encrypt available, the browser makers are now talking about penalising all HTTP sites. Next year, or the year after that, they could decommission Let's Encrypt (or start charging), and suddenly we'd all see what had been lost: it'd no longer be possible to set up an unpenalised site for free.

Personally, I believe that an IP cert should be issued along with one's IP address, and a hostname cert should be issued along with one's domain name.

If LE goes down, your cert expires and doesn't update, then your website visitors get the "unsafe site banner" and have to navigate instigation of an override to even see your pages.

My small business page's cert got messed up (by Plesk, or the hosting provider I suspect) and the page went offline.

If your site being essentially unavailable to customers isn't a major consequence I don't know what is.