Open access (OA) is becoming a standard practice in academic publishing. It is no longer limited to journal articles - books, reports, datasets, even research methods and peer review processes are being made publicly available in open access.
Most publicly-funded research bodies recommend or mandate some form of open access: the results of tax-funded work are required to be made available to the taxpayers.
Publishing open access is important for research transparency and accountability. It is the best practice to ensure the integrity of research practices and results.
Open access is a mandatory requirement for REF eligibility.