What makes it more expensive? A certificate is free (With LE or self-signed), the performance impact is negligible and there's a clear reason for why everyone should be using it.
And, as wonderful as LetsEncrypt is, it's not forever. At some point, they're gonna' get tired of messing with it or it will get taken over by private equity (see .org) and for whatever reason, it won't work any more.
And sure, that's always been true, new stuff obsoletes old and things fall by the wayside. But my current browser can access modern websites as well as sites from the dawn of the Web. But FireFox 85, 87 or 90 will probably make https mandatory -- and that amazing continuity is gone.
• https://news.ycombinator.com/item?id=21912817
Some websites are the equivalents of billboards.
The cost is dependence on a central authority that can make your site inaccessible in a whim.