We have started rolling this change out with the April Current Channel updates (Builds 9330 and beyond). As such, it makes sense to make this as broadly available as possible. As your comments have indicated, Power Pivot has moved from targeting a specialized audience to generally useful capability for working with data in spreadsheets. In this case, a decision has been made to have Power Pivot be available in all Windows editions (“SKUs”) of Excel! This means the Business, Home, Standard, etc.
I’m happy to announce that your input has had another direct impact on the product. Microsoft has just announced that Excel Power Pivot will now be available in all Windows editions of Excel, which is awesome news and a step in the right direction.