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!
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?
Using the hotspots doesn't check you in; checking in allows you to use the hotspot. Seriously, read the page before spewing FUD.