Because they won’t return your money, simple as that.
I was reserving a flight with one of the LCCs, and was offered a flight insurance. I was fed the usual mumbo-jumbo, but I thought what the hell, it can’t be that bad. Well, I was wrong. When I had to cancel the flight, I found out they don’t have an email where you can ask for help. You can only call a phone number, from 8-5 (their time), and to top that off – a paid phone number.
After you reach them, and they take your initial data in, they insist you download some forms from the web, fill those forms, and send them back to them @ land mail. I did that three times, however – and who could have guessed this – they never received my forms. I should point out that I had a receipt from my post office that it was, in fact, delivered.
In general, their whole service oozes with the ‘we will never say we won’t or can’t help you, but we will do our very best to do exactly that – being polite in the process’ type of attitude.
Never, ever, ever, use this travel insurance.