Appeal to Common Practice
"As a point of democratic principle, how can something that most of us do be illegal?"
Your argument is an example of "Appeal to Common Practice" and therefore fallacious.
I am not disagreeing that copyright laws and the punishments are a crock of shit that favour the BPI/RIAA over the artist/consumer, but you need to construct a better argument to stand a chance.
How about "The proposals entrench a business model that is slowly becoming out of date and creates artificial barriers to trade. This stifles innovation, the economy and start-up business to the benefit of the incumbent players and reduces the ability of workers within the industry ("artists") to earn a fair wage, expect for a few big-names. It should not be up to the state to protect someone's business model (or protect them from their poor business choices) except in absolute extremis where the stability of the state itself is affected. The state should ensure that its populace are served by businesses that work for that populace and provide them the services they want, rather than assist business to work against the wishes of the populace."
1 - Get rid of DVD region-locking (regions are fine, languages and all, just no locking please).
2 - Allow me to format shift for my own use (not legal in the UK).
3 - Allow free trade (grey imports etc, this will reduce price-fixing).
I am sure you can think of more.