Joel has said in the past that nothing has increased sales more than adding new features. I've always wondered how he reached that conclusion and what data he used to arrive at that. (it doesn't necessarily follow that if subsequent releases generated more sales and had more features, then it's because of those features that sales were made).

Generally I've found that simplicity may not create marketing buzz for your product but will result in more people actually using it (sadly people using != more sales all the time). That's why people still use excel instead of the enterprise crm/erp system that their COO bought.