The other part of the equation: The internet is an important aspect of the current generation's identity and culture. What seems like addiction to us could very well be our children's identity, lifestyle. The comparison to TVs is flawed because TV is not social. The unhealthy aspects have to be spoken about in the same vein as drinking and drugs, but any kind of limit-setting that doesn't acknowledge this might push children away from conversation.
There is an hilarious episode of Everybody Loves Raymond that goes into this with refreshing honesty.