The reason they are forcing people is so that they can pad the subscription number when they report to investors. It is a very shady grey area and while not technically illegal is a poor way to do business. I would not be happy as an investor to be given padded data.
I'm afraid of identity theft are their firewalls really safe?
Absolutely NOT. It is completely untested and will be under extreme attacks by the hacking community in the coming weeks. Many new companies holding account info are breached within days and ESO has a huge target painted on its forehead right now. I do not advise using your real info, ever. I do not , nor have for years.
If you don't want to give your credit card details etc for any reason you can simply purchase a time card, you should be able to get a 60-day time card from any game retailer, if you can't get one locally try Amazon.
Elder Scrolls gaming since November 2002 (Morrowind, Oblivion, Skyrim & Elder Scrolls Online)