Guest networks are socially important, and friendly, no matter how much the cable modem companies dislike sharing. Unfortunately the WiFi encryption standards assume that if you want privacy you also want to limit who can use the network, so if you want encryption on a guest network you need to resort to approaches like your SSID "passwordispassword".
For a long time, most of my neighbors and I ran unencrypted networks, so if my DSL was out for a day, I could borrow a nearby "linksys". (When 802.11g came out, most of those routers got set up with passwords, so I'd have to go over to Starbucks if my DSL was down.) The only problem I ever had was when one of my neighbors got a virus and her PC used my Wifi to spam. Fortunately I have a friendly ISP, so they just called me and said "BTW, we've blocked half a million spams from your line today, can you see if it's your PC or your Wifi?" One of my friends considered it a civic benefit to run Wifi so his neighbors' teenage kids could have uncensored Internet if they wanted - was fine until the kid discovered file-sharing and flooded the airwaves.