I take my Chromecast on holiday, you basically have to factory reset it every time to change network. But my recollection is that you’ve always had to do that.
My solution: get a travel router and have it broadcast the same SSID (and use the same password) as you use at home.
All your devices should successfully connect to it and you don’t need to factory reset them.
Many of them have the ability to navigate through a captive portal too (since I got mine all the hotels I’ve gone to have just needed a password, so i haven’t needed to test that).
I have a travel router as well, I just prefer to keep the SSIDs different. It is definitely paranoia, but if someone sees your travel router at a hotel, they know your not home, and your home can be found on wigle.net.
Its not that bad to reset the Chromecast, and I do it infrequently, so I’m happy with that.