Same reason everyone else does: to weigh in on some issue.
And if Laci was YOUR daughter? You'd be, what?? Fishing?
If she were my daughter, I'd take an interest. Since she's not, I don't feel a burning need to know every nuance of the trial of the murdering dirtbag who killed her. Try him, fry him, and tell me at the end of it. I don't care what Geragos had for lunch or the expression on the face of the third juror.
You weighed in to weigh in..
Greaaaaat.
And you don't give a whit. Even more important. doh.
If you don't have a burning need to know, again, you still have some need to speak.
I had a sister in law murdered in Modesto. Never solved. All cases solved are more than passing interest. Justice served, is all a family gets. Sometimes, it never comes at all.
I don't give a crap about Gerragos' lunch either, but it's a nice way to change the subject.