Microsoft: spread the disease, sell the snakeoil
Some companies, with a vested interest in making sure more copies of Windows are sold, seem to think it’s a good idea.
Personally I think making you pay for Windows (either off–the–shelf or pre–installed on a new computeralso known as the ‘Microsoft tax’) and then expecting you to pay for a subscription to clean up the mess it leaves you with, is not just immoral and contemptible, it’s criminal.
Of course, if you have more money than sense or no sense at all then it’s probably a good idea to sign up. Otherwise, I’d suggest either using one of the non–Microsoft anti–virus services (some are free) or dumping Windows altogether.