Typically features like this are disabled by default for Workspace so that admins can opt-in to them. This has happened for years with many features. Part of the selling point of Workspace is stability and control.
In this particular case, I would guess (I have no inside info) that companies are sensitive to use of AI tools like Bard/ChatGPT on their company machines, and want the ability to block access.
All this boils down to Workspace customers are companies, not individuals.
I think they don't know their market. For every IT guy who doesn't want users stumbling across a new Google product at work and uploading corporate documents to it, there is some executive who hates their 'buggy' IT systems because half the stuff he uses on his home PC doesn't work properly from a work account.
The smart move would have been for workspace accounts to work exactly the same as consumer accounts by default, and then something akin to group policy for admins to disable features. For new stuff like this, let the admins have a control for 'all future products'.
This works the other way though, Google adds a new button to Gmail and the IT illiterate exec gets in touch to ask what it is or clicks it not knowing it does something they don't want to do, and suddenly the IT team find out from users that their policies and documentation are out of date.
It may not be the option we like as tech-aware users, and I've found it annoying in the past at a previous role where I was always asking our Workspace admin to enable features. But, I don't think it's the wrong choice.