Particularly in genre fiction, where we are often creating entire worlds, cultures, words, economies, histories, the facts can be thrown too fast. When the author has been spending ages creating a world, she can assume that to toss the reader right into the center of it will be just as interesting to the reader as the writer. If the reader doesn't have any familiar image, emotion, or sound with which to identify, it's all so much alarum and excursion. A character with a need is the simplest beginning. This leads to another need, more action, more information, the facts and the pacing proliferating one at a time, until the reader sees and empathises with the characters at hand, and reader and story are launched onto their partnership, which will endure until the last page.
Action is probably the safetest hook.
But I don't think that Reaction should be dismissed, because sometimes Reaction to an event that just took place can clue the reader in to the characters and their needs just as fast. Their immediate need is to meet him first. By the time the family hash it out, and find out that the father has already met the young man, we have a fair sense of every single one of the characters, and we're ready for an action scene. Cosmic Backstory openings are dangerous because with no stake for the reader, they're just an encyclopedia article. Likewise, in medias res openings can be dangerous because important facts can slide by and the reader is galloping along so fast in that otherwise admirable brisk pacing she will miss what's important and what isn't, get exasperated, and just leave.