It depends on your PROJECT requirement. Customized cubes are not mandatory for all the projects. If your business requirement is differs from given scenario ( BI content cubes ) then only we will opt for customized cubes. Normally your BW customization or creation of new info providers all are depending on your source system. If your source system other that R3 then you should go with customization of your all objects. If your source system is R3 and your users are USING only R3 standard business scenarios like SD, MM or FI... etc., then you dont want to create any info providers or you dont want to enhance any thing in the existing BW Business Content. But 99% this is not possible. Because surely they should have included their new business scenario or new enhancements. For example, In my first project we implemented for Solution Manager BW implementation. There we have activated all the business content in CRM. But the source system have new scenarios for message escalation, ageing calculation etc., According their business scenario we couldn't use standard business content. For that we have taken only existing info objects and created new info objects which are not there in the business content. After that we have created custom DATA source to info providers as well as reports.

It depends on your project requirement. Customized cubes are not mandatory for all the projects. If your business requirement is differs from given scenario ( BI content cubes ) then only we will opt for customized cubes. Normally your BW customization or creation of new info providers all are depending on your source system. If your source system other that R3 then you should go with customization of your all objects. If your source system is R3 and your users are using only R3 standard business scenarios like SD, MM or FI... etc., then you dont want to create any info providers or you dont want to enhance any thing in the existing BW Business Content. But 99% this is not possible. Because surely they should have included their new business scenario or new enhancements. For example, In my first project we implemented for Solution Manager BW implementation. There we have activated all the business content in CRM. But the source system have new scenarios for message escalation, ageing calculation etc., According their business scenario we couldn't use standard business content. For that we have taken only existing info objects and created new info objects which are not there in the business content. After that we have created custom data source to info providers as well as reports.