Given that my wifi has good password protection and is only used in my home, is the randomization of my wifi really necessary?
Not really
If you’re running only IPV4, probably not if you have a good up-to-date router set up properly (with firewall protection), and (optionally) software firewalls running on your end devices. If you’re running IPV6 to the Internet via the LAN and no use of VPN, then yes, you should use MAC randomization.
Password-type security really doesn’t have anything to do with this; it is about broadcasting your IPV6 address to the whole world which invites IP-based attacks of various kinds.
I turned off my firewall for a few minutes the other day when reconfiguring the LAN and there were tens of attempted attacks during that time and not even related to IPV6.