Crypto is/could be still fine, it will still make it harder for others to see the contents of the conversation that is going on between the two machines.
What you are losing is the modicum of confidence that a website is the real deal because another party (that browser and OS manufacturers trust) took the time to, at the very least, verify ownership of the domain.
Automatically trusting any cert raises the bar for attackers from passive snooping to MITM. On a home LAN/wifi, MITM is pretty much as likely as passive listening. At the very least you need TOFU (trust-on-first-use) for any kind of real attack prevention.
