In one of his latest essays "The truth about Google's so-called simplicity" Don Norman discusses the simplicity of Google, or especially the first page of Google's web site. Norman argues that Google "is deceptive. It hides all the complexity by simply showing one search box on the main page". The main argument from Norman is that all the other search sites offer much more on their first page, but at Google you have to click to a second or third page to get to other functions than the plain and simple web search.
It seems that Norman finds this to be problematic and not "fair". I think that Norman touches upon another issue that for a lot of people is more important than the ease of use of many functions, and that is separation. Norman writes "Why isn't Google a unified application?". I think we can argue the opposite, namely that it is exactly that fact that has made Google so successful. It might be the case that people don't like "unified" products. We know from the field of home electronics that the most successful products are simple and often single function based. Almost all attempts to design multi-purpose products have failed. This can be seen in many other design field as well, like for instance kitchen utensils.
So, maybe Google strategy to be "deceptive" and not to build it first page design on its organizational structure (another argument from Norman) is what people find attractive and useful.
However, as with all designs, people get tired of a design and want variation, and one day we will see someone who designs a new search page in a (probably completely different) way that will attract peoples attention away from Google.
For any committed designer (and design student) a design like Google.com is a perfect object for analysis and critical reflections around quality and design principles, especially to compare and contrast the Google site with other (equally successful) but totally different designs and try to make sense out of the differences. This is probably one of the best learning activities that will prepare a designer for any future challenges.