This is being done with the best of intentions but browsers scaremongering over HTTP sites as if they are dangerous is a bad thing. There is more to the web than commercial transactions!
Human people cannot feasibly be cert authorities. Only corporations can. When browsers will only display sites that are authorized by corporations we're eventually going to be in big trouble. Yes, LetsEncrypt is a benevolent corporation, yes there are even options beyond LE, but as we know from the dot org fiasco as long as there is potential money to be made these benevolent dictorships will eventually go very bad. And that's ignoring all centralization making a very juicy target for government censorship.
Encrypt, yes. But also allow plaintext. The potential for a down-grade attack on a "secure" site is worth far less to the world than being able to communicate person to person without a corporate intermediary approving every bit.