Assume Wifi is Secure by Default
Looking at the list of Wi-Fi networks in the panel the lock icon (for secure networks) is the common factor to the majority of networks, and given that an unsecure network is more often the not the uncommon case we should assume secure by default, hide the lock icon, and display an icon when an network is unsecure (given that is more noteworthy).
Something like this:
(a bonus effect is the shaming of unsecure wifi)
I'm taking inspiration from how Chrome treats it's security indicators for HTTPS: https://blog.chromium.org/2018/05/evolving-chromes-security-indicators.html
Edited by Sam Hewitt