The cost to go to a movie theater should cost a lot more than a remake of a 25 year old NES game.
Multiple parties are involved that are out for a profit with much more at stake financially than here (The theater owner, the movie distribution company, etc.), you're paying for the production cost of the movie (Which is typically many millions of dollars... something which in the videogame world usually calls for a $60 pricetag rather than $15), paying your share of the upkeep of that building, lease or mortgage cost, the wages for the service employees manning it during your stay, paying for the experience, etc.
If I was paying $15 to go to a movie and the cost involved were the same for the parties involved as a game download I was considering that I could get more than two hours out of, I'd agree that there's no logic for that line of thought. But beyond being two entertainment options at a similar price (Although around here, tickets are about half of the cost of this game), they're not comparable I'd say. I think most people realize that the cost to go to a theater is far greater than it is for a $15 XBLA download so they adjust what they consider a reasonable price accordingly to reflect the differences. And the experience is also not the same since many moviegoers will tell you that the experience goes beyond just enjoying the film itself. And I suspect for many gamer's, they tend to be buying downloads more frequently than they'd go to the theater leaving more reason to carefully consider their purchases since they're happening more frequently.
Even just at $5 a pop, your investment can get up to a surprising amount in a short amount of time if you're frequently making impulse buys on these download services. I think I've been to the theater once in about the past four years by comparison. It's something to keep in mind both for your wallet and if you're a classic gamer that cares about the day when the Xbox 360 isn't a commercially active platform.