If nothing just for the complexity
Microsoft has always favored complexity over simplicity. if not just for the fact that add-ons offer more flexible options. It's easy to change individual options and only would affect those that have that option, whereas if they want to change an "E7" subscription, it would trigger more customers looking at that level.
Just look at their Azure Entra pricing. Confusion with the likelihood of paying more than one has to (absolutely, with the offering's structure intentional by design). MS Management may be greedy, unethical a$$h#les, but they're not stupid greedy a$$h#les. The philosophy of complexity permeates the company. For another example of complexity, look at their Terms of Service documents...
For smaller companies that engage with MS at the subscription level, I fear that one day, the Management (or the owners) of those companies are going to wake some morning and realize that 50+ % of their profits/revenue are now going to M$ and not a damn thing that they can do about it.
Subscriptions/Services (where this is no/little competition) are evil. If your data is not on your hardware/premise, you don't own it. Period, It's that simple.One can rationalize pretty much anything, but it doesn't alter the age-old adage: "possession is 9/10 of the law". Maybe the GDPR helps, but not anywhere outside of the EU. Especially if your company's size is in Microsoft's business "noise". Do you really think Microsoft cares about your company or you?