Inexpensive boxes are for everyone. They're for the kids, the hobby-ists, the completionists, the set-builders, and even for the big spenders, as they often just want to buy some packs. The big hits aren't always available but you get lots of cards for your money.
Expensive boxes are for the investors and the thrill seekers. Everyone enjoys the excitement of the big hit and sometimes these packs provide them. These packs usually contain autographs and memorabilia cards, short prints and inserts.
For me, I want the hits. Especially autographed cards. With the number of cards in my collection, hundreds of commons just don't appeal to me. Breaking open boxes of lower-end products just leaves me with more and more of them. I just don't have the room.
As for justification, just think about it. I can buy three or four boxes of lower-end or mid-range product and get four or five hits total as well as hundreds of commons... or I can buy one high-end pack for the same total price and get four or five hits and virtually no commons. Plus, often the higher-end products contain more celebrated players.
For my player collections, which need the low end cards and commons, I can just trade for them or buy them off eBay.