As it stands now, many locations still have only one option when it comes to high speed internet (excluding satellite, but that's not really high speed). Comcast is now trying to merge with Time Warner. Talk about one hell of a monopoly.
Now they argue they don't compete in enough markets, but think about it, it's the internet. With a combined merger, they will have a much easier time charging content providers for bandwidth to costumers.
So now you, the customer, are going to be higher premiums for any online services such as Netflix, Amazon Prime, etc. Because when these companies have to start shelling out to internet providers, they have to raise their prices in order to stay profitable.
So having these huge open wifi networks seems like a good deal for a consumer, it's actually just a way for these companies to get increased revenue, using the bandwidth you've purchased from them, extending it "freely" to other people, and using this as a way to entice companies such as Netflix to pay them a higher streaming premium.
Basically, and in essence, this is a way for Comcast to extend it's user base without extending it's customer base, to leverage higher bandwidth fees from content providers.