Configuring preferences and options in Outlook.com
It most certainly has been a feature: https://support.office.com/en-us/article/get-a-personalized-email-address-in-office-365-75416a58-b225-4c02-8c07-8979403b427b
Get a personalized email address in Office 365
Outlook.com
As a benefit of your Office 365 Home or Office 365 Personal subscription, you can create a personalized email address that's associated with your Outlook.com mailbox.
Getting started
To get started, sign in to https://outlook.live.com and make sure you're using the new Mail experience. Select the diamond icon on the toolbar to open the premium dashboard. Under Personalized email address, select Get started and follow the instructions.