Whilst I didn't agree with the cards being biometric, because that's just another government database for some nonbody pencil pusher to lose data from, I do support the idea of ID cards themselves.
I'm a british citizen by birth only and have liver around the world. I'm currently at university in the UK but I live in Belgium out of term time where there are ID cards and until recently (last year I think) I needed to have one. It used to be merely a piece of card with much the same info as your passport, but more portable. I mean yes now the new cards are "e" cards, essentially biometric (not quite) and I don't even need one, but it makes things so much easier for me that I decided I might aswell get it.
My problem in the UK is that because I don't have a driver's liscense (yet) means that my only form of ID is my passport, which I don't really want to carry around on me the whole time incase I lose it/it gets stolen which is why I think ID cards would be a great idea but only if they're not biometric as the government already has enough data on us (and far too much to leave lying around on trains.....)