Just like all other "optional" features Facebook has provided in the past, they will inevitably figure out a way to hide the fact that using these hotspots checks you in, and probably spams your "friends" with a record of whatever you ate.

It is not optional for users who do not have Facebook.

Let's see:

My desktop machine is harvesting all sorts of information on me and Google can probably identify me with ease.

My mobile phone KNOWS what my contacts are from services I haven't even installed yet (WTF!).

Facebook tried to sneak in even more permissions on my Android device a couple of weeks ago (deleted it since).

It seems every time I lose more and more and more anonymity, and guess what: The 14 year old me from the past didn't care, but the older I get the more I want services to leave me the fuck alone!

Define: "optional"

Optional as in "you can't use WiFi if you're not on Facebook"? As in, with each coffee I buy here I contribute to paying your WiFi bill (both hardware and connectivity) but I cannot use it, thus having to pay a premium to get a better 3g subscription so that I can work without WiFi?

As a rule of thumb, what's good for facebook is bad for everybody else. A transnational corporation whose business is surveillance and data gathering planting devices in local businesses replacing wifi internet access by "you don't get to use the internet if you don't submit to our corporate surveillance" is not good news. Telling a portion of your customers to go fuck themselves is not good for businesses and this is what such facebook routers are doing. Replace facebook by NSA here and say again you don't see a problem here.