1. Familiarity
The most successful websites have a classical aesthetic: Facebook, YouTube, Flickr, Wikipedia etc.
We build new social websites every day in the hope that users will flock to them. The truth is, people spend most of their time on other sites. Like the sites mentioned above.
Familiarity is a powerful thing. As designers, it is something we must embrace.
"The familiarity heuristic is based on using schemas or past actions as a scaffold for behavior in a new (yet familiar) situation. This is useful because it saves time for the subject who is trying to figure out the appropriate behaviour for a situation they have experienced before."
I'm not suggesting we should go out and copy the aesthetics of the big social sites. We just need to realise that a clean, ordered, classical style is a familiar look to millions of web users.
2. Speed
According to this new HCI study, users care most about speed. The study says:
"Speed is more than 18 times more important than customization, 5 times more important than content density, 4 times more important than adaptive behavior, and 3 times more important than minimal memory load. These results show the importance of a responsive interface..."
Essentially, social sites are interfaces that expose social objects. The interface needs to be fast, in order to satisfy. The classical aesthetic is free from unnecessary adornment. It means pages can be light and nimble, empowering people to be sociable around the objects that matter.
3. Readability
Mandy Brown seems frustrated. She thinks that "readers remain a neglected audience" on the web (read more of Mandy's thinking in In Defense of Readers).
Mandy also says:
"Whitespace is not so much a luxury as it is a prerequisite. Every pixel of whitespace around the text can help the reader stay focused instead of wandering off. A readers’ eyes must repeatedly approach the edge of the text block; a sidebar that is set too close to the text—or one that is brighter or darker in color—will compete with her on every line."
In response, Arc90 built the READABILITY tool to make reading on the web easier. It's an excellent tool that basically removes the "clutter" from the page.
Clutter is anything on the page that distracts a user from reading or finding relevant information. Social sites are all about relevant information. The classical aesthetic naturally reduces clutter.
4. Maintainability
Building and maintaining a social website requires a lot of UI design.
First, the core pages get designed - Homepage, profile page, search results etc. It's easy to think that this work represents the bulk of the design work. Well, it doesn't.
Social websites are made up of oodles of bits of UI, messages and flows to enable a myriad of interactions to happen. This stuff gets figured out right up to launch, and typically takes 20 times longer than creating the core pages.
After launch, a social website is in constant maintenance and development, growing and adapting with the community. Over time, new features are designed and implemented to satisfy the needs of the users.
A classical aesthetic is easy to build on. Look at Flickr, for example. When Flickr implements a new feature, I imagine they require very little visual design resource to make it happen.
Conclusion
The big social websites are successful for a number of reasons. Without doubt, one reason is because of the classical aesthetic they adopt. Familiarity helps people to feel comfortable. Simplicity allows interfaces to be light and snappy. Ordered, clutter-free design makes reading easy. And minimal style enables the roll out of new features and UI with minimum fuss.