Have a big Warning when creating the tenant that the name cannot be changed. Now many users are stuck with bad sharepoint url names.
David Wallach commented
Yes, we also went though agency name change recently, unfortunately right after migrating to O365. So to endure another migration (all content from SharePoint, OneDrive and Email!) just to achieve a more appropriate URL seems to be an awfully high price to pay for this truly common occurrence. This really needs to be addressed. Thank you!