This may be shocking to some of you, but some people don't like browsing porn at all. But ESPECIALLY when at work or at home when their kids are sitting next to them. There are thousands of reasons why people don't want unexpected porn showing up on their computers.
Your kids are going to stumble onto porn on their own. Better that you set an example by saying "ick" and closing the window with them around.
OMG, my Chumby just spontaneously rebooted itself.... (unrelated to porn, but it honestly just rebooted)
Why is Apple against porn? I thought everyone liked it.
And this may surprise you but some people do like browsing porn. Oh, Wait, Steve was against porn and we all must blindly adhere to his idea of morality!!!
LOL.
Explicit erotic imagery predates the late turtlenecked overlord by millenia, and will probably exist for millenia after his demise.
(I say "probably" because there's a chance that a collision with a large asteroid could destroy all human life on the earth - not because there's a chance that people will stop enjoying explicit erotic imagery.)