I think they had to because Fox was not involved in digital distribution.
I understand why they initially pulled the logos - they wanted digital versions up very, very quickly, and hadn’t worked out a better deal with Fox - before buying them outright, that is - what I don’t understand, especially considering their strategy for The Force Awakens and every other movie that followed, is why they thought the Lucasfilm logo needed a fanfare at all, much less the chopped up “Finale” from Empire as that fanfare.
Everything about it just sounded like a thing decided upon, started, and finished in less than an hour before someone hit publish.