UPC does this too
UPC in Hungary, Switzerland and as far as I know in several other countries does this too. They call it Wi-Free. It also gives their customers free wifi access in other countries. In the case of UPC Hungary I had to get a password for this and I find a nice convenient free wifi as I move around the country. In theory you can not log on to your own Wi-Free router, but nothing prevents you logging on to your neighbour's. You have the option of disabling this service if you do not like it. It does not effect your own speed and monthly limit, if any. I see no extra problem with hackers, I can not see how hacking a system like this would be much easier than hacking your regular wifi router.