Because the UK Government respects peoples ability to make their own decisions and choices?
Or maybe the UK Government hasn't been paid off by Harrahs to pass an online gambling ban through the back door?
Seriously though - I think the UK simply recognises Poker as a sport / game that alot of people enjoy and play, and not as some sort of degenerate activity where everybody is going to lose their life savings.
Plus what the US have done is just underhand and wrong, so why would any other countries support it?
To think of all the support the UK have given the US over political issues over the past 10 years or so, and how they stood and backed the US up, only for the US to do something like this and wipe $billions off the London Stock exchange.