The question was: IF the cashout is always made outside Poland, what's the benefit of using a polish ip and number.
I'd say the ip and phone are pointless.
If a bank is trying to prevent foreigners from buying their prepaid cards from Poles, it may be beneficial for you to fool them into thinking that you're a Pole that likes to travel by first logging in with a Polish IP address after buying it.
I'd call that a long long shot...
polish banks are not to be trusted.
But if it works...