Research has shown that open access-publications are cited more often than articles published in closed subscription-based journals (see for instance the Open Access Citation Advantage Overview/Sparc 2015).
According to the Åbo Akademi Policy for Open Science, research conducted at ÅAU should be published as openly as possible since open science is responsible research practice. There is a national policy for open access for research articles in Finland. Also, more and more funders recommend or even demand that research outcomes are made openly available. For instance Academy of Finland and the EU within Horizon2020 require that the publications which arise within the research that they fund be made open access (green or gold).
Making research outcomes openly available helps to democratize research, improves research communication and evens out the differences between the research institutions in different countries, but also makes research outcomes available for other professionals (such as physicians at health centers in municipalities who can't afford subscriptions). Although the broader audience is not susceptible to some of the technical vocabulary used in scientific writing, availability in principle and the possibility to check results which it brings with it may contribute to the legitimacy of research.
Kuva: AJC (CC BY-NC-SA 2.0)