Yes, a lot of it probably is porn. However there's tons of academic and technical info too, and all of it which is that "other" 99.996% of the content of the Internet that's considered the "Deep Web". Information that's accessable, or public, but is not indexable due to the way it's linked, or is indexed only superficialy at a high level.
The analogy on your own desktop computer is the difference in time and effort between searching by file names vs. searching the actual contents of the files.
The group that can figure out a method to efficiently search and crawl the "Deep Web" will be able to write their own ticket. And assuming they aren't Google, they will be the "next Google".