I'd be perfectly happy for major porn sites to be blocked by default, as long as ISP customers can just go to their account online and toggle a checkbox and be done with it.
Google images blocks "adult" pictures by default doesn't it? Why aren't we having the same conversation and upset with Google images? Perhaps because all it takes is toggle the filter off in the menu.
Their proposal to block sites without age verification is pretty dumb though. Any kids can get through that, and it doesn't give any power to the parents to block these sites.
edit: I guess as usual the difficulty is in having rules that can be clearly defined, so "age verification" just fulfills that. But if they already have laws to categorize pronography I don't see why they couldn't apply to setting up "default" filters. Especially if looking at commercial pornography sites. I think commercial ones are the most damaging because their drive for money is what pushes them to create the most extreme and dehumanizing content.