Yes, but someone also has to pay for the work that goes into the bespoke "Export data as" button, or IMS Enterprise or numerous APIs. The benefit of using SIF is that the ZIS can be used to allow multiple applications (and institutions) to share data.
Take a look at this presentation from an assistant head at one of the schools involved in the SIF Association. He illustrates a number of the benefits of implementing SIF: reductions in bureaucracy, improving the quality of data, improving data security, freeing up time for staff to teach, improving child safety etc. He also estimates that his school could save 400 hours a year on data management by implementing SIF.
SIF can help improve data quality as you can enter data once into the MIS rather than having to retype the same info into every application and means you don't have to manually update every app when some info changes.
Rather than relying on Census to cleanse data, it would be better to have processes in place to ensure data is up to date, relevant and accurate. Becta's Information Management Strategy Framework may be helpful in doing this :-)