One difference, the rest of those events are included with the gate. HHN is an upcharge so with the money it generates it should have priority
In totality though, it IS the priority. Universal dedicates more money and resources to HHN than any other event. They hire more performers, pay more overtime to support staff, and spend more money on temporary construction than any other time of the year. And that shows in the quality of the product on the guests' arrival. A&D, Operations, F&B, Entertainment, Events, HR, and yes, even Marketing, put more effort into HHN than anything else. I'd argue they put more effort into HHN than any other Orlando parks' event.
When HHN marketing is looked at in a vacuum, it's a disappointment. It feels like an afterthought. BUT-
Do any other events get a slow roll of information to engage the audience? No. Mardi Gras, Concert Series, etc, just gets dumped in a blog post.
Do the other events have their own, "independent" social media presence? No.
Do the other events have their own, independent website? No. They have landing pages on the resort site.
Marketing does everything; all events and the resort itself. While the HHN fans were complaining about Marketing "doing nothing" in June, Marketing was focused on promoting a new water park (which should be a higher priority). Look around at other theme park haunts and compare. You'll see that Universal is still (arguably) the best in the business.