Sure they are! Complicated interfaces make it easy to:
1 - avoid forcing yourself to really prioritize your feature set, something that's really hard to do and requires really understanding your users.
2 - push a bunch of effort from you to the user.
For example, you cited A9.com. If I do a search on A9.com, the search results window is split (by default) into two parts: one that lists web search results and one that lists book search results. At least by default, it appears that both sections are always there.
If I do a search on Google, than Google will usually only display web search results, but if it senses I'm searching for something about a book (example: do a search for "Charles Dickens"), you'll sometimes see some book results up at the top.
Google's method of only showing you book results when it suspects you are looking for something having to do with books is both much less complex for the user and much more difficult to build.
1 - avoid forcing yourself to really prioritize your feature set, something that's really hard to do and requires really understanding your users.
2 - push a bunch of effort from you to the user.
For example, you cited A9.com. If I do a search on A9.com, the search results window is split (by default) into two parts: one that lists web search results and one that lists book search results. At least by default, it appears that both sections are always there.
If I do a search on Google, than Google will usually only display web search results, but if it senses I'm searching for something about a book (example: do a search for "Charles Dickens"), you'll sometimes see some book results up at the top.
Google's method of only showing you book results when it suspects you are looking for something having to do with books is both much less complex for the user and much more difficult to build.