Didn't read much of the thread, but what I can tell you is that if you want to sell these warranties, you have to pry a little bit into the customer.
If they have kids, you can make the point that kids like to play with things, and that anything they do to it could be taken care of with this warranty... things like that. There isn't a general statement that can get someone to buy into the load of crap, you gotta find a way that fits the person. Aside from that, pushing the ease of making a claim versus working with a manufactuere'rsersrsr RMA service could be a push in the right direction.
Also, as much as I hate to say this... push push push push! keep talking about the warranty. Remember the rule of 3 no's. Until they say no 3 times, they don't mean it. When you go to ring someone up, make sure you casually slip in "and you wanted the warranty, right?" you might get some idiot not paying attention who will just babble a yes then hand you the credit card and sign away without even noticing. Worst case scenerio, they complain to your manager about your sales tactics, in which case the second you leave he congratulates you on doing your job the right way.
Most people give up to early when trying to sell something... the thing is, if you can't think of a good reason for a person to need this, neither can they. Be creative. Chances are if you are asking someone about the warranty, they are going to purchase the product anyway, so it's not like you have to worry about scaring them out of the store. Sure, they might not come back, but why should you care?