Sounds like you really are not their target market. The primary money making target for Disney is people who watch it on their smart tv. Even if the average joe does decide to fire up their mac they won’t care if it’s not 4K.
Some people don't care about 4K. Other people think they care about 4K but don't really know the difference.
They compress and screw up the video quality so much that even calling it 1080p is a stretch in my opinion
Most people have houses/screens too small for 4K to be visible anyway, though, so I guess it's easy to get away with providing such a crappy service