Well, not much to add, Gostev
In my already expressed opinion, mailboxes and OneDrive, have different aspects, than SharePoint. Mailbox and OneDrive can be easily seen as a per-user (private) stuff. And even then, with something like OneDrive, I am not much worried here, as it could be considered being kind of a backup already. Now I know, that professionals don't want to hear that
But typical admin situation is to tell users to back-up to some company storage - but most users ignore that. So having OneDrive already kind of works as a backup. With the trashcan, you can cover even the eventual mistake when user deletes something. So - in our case, we were thinking mostly only to back-up OneDrive accounts of a management (top + middle), not the whole company workforce.
With the Sharepoint, we can see different aspects here. We have decided to not build an on-premises farm. But that means, that you have your data in one place only - in a cloud. It's kind an opposite to user based OneDrive. That's why we have expected per 1TB pricing, or per site one. If you add few new users to your site next week, will you have to adjust your licensing? That stuff can be quite danymic, as users will be added to internal sites on a per project etc. basis, some sites are going to be scrapped / archived, once project is finished, etc.
So, that's why, in my opinion, your recent SP licence pricing does not much the nature of the Sharepoint ...