But judging from the response here, clearly lots of other people think of the box as a part of Comcast's infrastructure that happens to be portable. And from that point of view, it makes sense for Comcast to eat the cost--just like they'll eat the cost of their cable lines being torn up in the hurricane.
And I suppose that if the vast majority of people have the latter view when they're signing up for cable, then Comcast should probably change their policies to fit that model, and just charge for loss or damage caused by the user.
Most rental contracts (for anything) that I've seen make the owner responsible for normal wear and tear and so-called "Acts of God".
If you rent an apartment, you're not generally responsible for the rebuilding costs if it gets blown away in a hurricane or tornado.
Here's an example lease:
Now it really depends on how it is done but when I had comcast I did the same thing and I was always able to get someone on the line to replace it on their dime because of the monthly fees. Granted I never have had a hurricane blow through an office I think most of the time they are willing to work with you.
If Comcast stuck a mandatory $3/month "cable box insurance" fee on everyone's bill people would be posting about how they are money grubbing assholes, but if they are effectively insuring all of their leased equipment against loss then they are doing exactly that except just not putting it as a separate line item on the bill.