Important psychological research - not

I hope they weren't paid a government grant for this:

"Imagine two servings of ice cream, one featuring a five-ounce cup overfilled with seven ounces, the other a ten-ounce cup filled with only eight ounces. Objectively the under-filled serving is better, because it contains more. But a study conducted by Christopher Hsee found that unless these two servings are presented side by side, the seven-ounce serving is actually considered more valuable. Apparently, people do not base their judgment on the amount of ice cream available, which is difficult to evaluate in isolation. Instead, they rely on an easy-to-evaluate cue: whether the serving is overfilled or under-filled. Overfilling evokes positive feelings while under-filling evokes negative feelings, and these feelings dictate people's evaluations."

Emphasis is mine. Isn't that the reason for the result, and does it tells us anything valuable?