Salesforce.com does a good job of providing a Forecasts tab for companies that really enforce this process, but IMHO this is more suited for companies selling specific products (usually with SKUs) that need to tie this information into their back-end systems. Is this the majority of users? I’ll boldly say that I don’t think so.
Even users that have the above situation may also not use forecasting in the system, simply because of the organizational challenges that seem to rear up when it comes time to forecast.
Many Salesforce users can live with their managers running an Opportunity Pipeline report to see what the sales team is hoping to close in a quarter. As long as the role hierarchies are set up correctly, this should be a piece of cake. And that report is a default one that’s already built for you. Take a look, and if you agree, you could even have your administrator hide the Forecasts tab from your users’ view, just to avoid complicating things.