It was mentioned in a Panel that if we ask enough they will do this. I suppose all we can do is keep asking.
Which is a bit shitty tbh.
Larian: "Beg us to graciously allow you to access level 5, something that is incredibly important to test and balance before BG3's full release."
Either Larian plans to release level 5 for EA regardless, in which case they should just tell us that.
Or they actually won't release level 5 if we don't ask for it enough, in which case they risk levels 5+ having terrible balance (and implementation) upon full release.