I didn't do that because of the hotspot issue. You could automatically connect to a hotspot with a valid IP address, but it wouldn't necessarily be active unless you clicked agree or put your card details in to buy time or logged in with an account.
It would be very annoying if you didn't want to use WiFi in a hotspot area and the phone kept changing your 3G connection to a 2G !

There could be any amount of time between connecting to a hotspot and getting a working connection, hence the polling.