It is easier for a larger audience to find open access publications than articles published in subscription-based journals. Previous research has concluded that articles that are freely accessible are read and cited more. (Swan et al. 2010 The Open Access Citation Advantage).
Research institutions and funding agencies recommend, or even require, that research results should be made freely accessible. In this way research transparency increases, the possibility of repetition and therefore, the reliability of the research, rises. For example, the Academy of Finland requires that the research they fund as far as possible is parallel published in freely accessible institutional repositories or databases. Likewise, research funded by the EU's Horizon2020 should be made freely accessible.
Research results made freely accessible democratize science, improve scientific communication and smooths out differences between various countries' research institutions. The website Open Science and Research lists benefits of open access publishing: