Could it be that it can bring Disney Plus everywhere (I assume they have distribution rights on their own media), while Hulu is a mishmash of content rights, and still hasn't made it to Canada?
It might also be branding - Disney wants everything Disney to scream DISNEY, as opposed to Hulu content.
One of the benefits sold to shareholders for Disney buying all of Hulu was that it potentially makes it easier for Disney as guiding force to negotiate international rights on all the Hulu content and make Hulu an international brand. Though how much of that is spin and will actually happen is a leftover question.
I would imagine so. Disney's biggest deals seem to have been with Hulu, so owning that outright gives it a lot of power to change deals, and with Netflix, which presumably part of the timing that Disney+ won't roll out until Fall is that coincides I believe with the expiration of the biggest of Disney's streaming licenses to Netflix (the one for access to films). (The Defenders MCU shows exclusive contract to Netflix I think will still take a few more years to expire before Disney can bring them "home".)
It might also be branding - Disney wants everything Disney to scream DISNEY, as opposed to Hulu content.