Bob

It doesn't have to be done, but it is recommended...as mentioned in the wiki and numerous threads, the main reason that is that it's simple proof for the kids years down the line when the OP has popped his clogs, so the kids wont' have to go through all the original lines of proof in the event they lose their passport or what not.

Also the kids are more than likely to be dual citizens and as US citizens need a US passport to travel, if they're babies, a UK passport isn't really needed unless you intend to move to the UK.

Best pro for getting US citizenship, you can bugger off if you fancy it and then come back if you don't like it without having to start from scratch...that and inheritance and pensions work out better for you.