The technology behind WolframAlpha is truly incredible. It's likely one of the most unvalued resources of our day.
The computational complexity going on is minimal compared to the effort it takes to create and maintain the dataset. Accessing it with a formal query language is then straightforward.
The parlor trick is making the formal query language seem as informal and colloquial as possible. But fiddle with breaking it and you'll see you're just running searches on very specific and very specifically tagged data.
Edit: Having thought about it more, the reason it's 'underutilied' is that it's actually not that useful. Your knowledge of its dataset is more important than its ability to provide it for you--witness the person below who knew that it could provide nutrition information.
Your index on its information is better than its index, in other words.