Honestly, I don't know why people are upset over this. The public network is isolated from your own. As far as I know it doesn't cause slowdowns on your network as the infrastructure supports much higher speed than what plans they offer. And you can opt out. Xfinity has been doing this for a while and it's one of my favorite features. Having access to high speed (25mbps at least) internet on the go is a huge benefit for me. If and when there are privacy or speed concerns, I'll complain. Until then, it's a feature. And I'm not a Comcast or cox fan, but when fios isn't offered, it's what's left.
It's probably been said 10 times over by now, but here are several issues:
1. You're paying for the device
2. You're paying to power the device
3. You are not receiving a discount for the two things above
4. It adds another SSID, which even if it's not being used can cause negative effects on wifi
5. If someone does use it, it could interfere with your own wireless and cause you performance problems
6. It can cause unwanted visitors to your house
Imagine if you were near a park, and you didn't have the option to disable this public wifi. All of the sudden you start having people congregating in your back yard, front yard, parking in front of your driveway to make use of the wireless from your device. That would get very old very fast, and it would be difficult to keep people away because of it's convenient location to the area. You weren't asked to offer this service, and you might not even know about it. Just all of the sudden you have people cutting through your back yard, leaving trash, lingering around, etc. You'd probably be quite upset and want this disabled ASAP once you finally figured out why it was happening.