I think the use of these kinds of insurance policies really depends on your financial circumstances, your attitude to risk and whether your the sort of person that will 'play the system' and claim to your advantage.
Personally, I couldn't do that. I know its the way of the world and most people do now, but I don't feel comfortable with it.
One of the best bits of financial advise I've read over the years is if its a policy you NEED i.e. House, car etc...then shop around EVERY YEAR for it and get it as cheap as you can (ensuring adequate cover of course but not over covered) and maybe asking for additions for free such as gadget ins on your house ins.
All the others are a waist of money if your not gonna play the game. If you add up all the monthly payments to insurances and extended warranties etc its a lot of money.
Chances are, if you actually saved that money or even half of it, you would have more than enough to cover any unexpected outlay's for a leaky tap, boiler breakdowns, a new tyre, a new phone. The chances of all these things going wrong at the same time is VERY unlikely......but that's where your attitude to risk comes in.
I've saved myself hundreds of pounds since realising this and I'm much happier for it.