If you own a boxed copy of Office I can understand why you don't get this for free. When you buy a boxed copy of Office 201x you should understand that you're buying a perpetual license to that version of Office. Expect it to work and receive bug fixes for a reasonable time (MS do 7 - 10 years of maintenance per major release?). But basically, no freebie big ticket features or upgrades to Office 201x + 1.
If you pay for the subscription, you're paying for a non-perpetual license in return for access to whatever the latest version of Office is. So big ticket features come free.
If you pay for the subscription, you're paying for a non-perpetual license in return for access to whatever the latest version of Office is. So big ticket features come free.