People often ask how it is possible that something as idealistic as Open Access (OA) has gained popularity and become a significant part of the scientific publishing market. I think, however, that it is more interesting to ask why it is not happening even faster? There are three important groups of factors that contribute to OA popularity:
1) benefits for authors (which was discussed here) ,
2) policies of public authorities and other grant funders,
3) current situation of the publishing market.
I will try to discuss each of these groups in turn, looking to identify the obstacles facing OA and retrograde trends.
Obviously, the Internet – the global computer network – is the main force behind each of these groups of those factors. The Internet allows an almost infinite multiplication of copies of any text, makes it accessible to anyone and (by and large) easy to find. Gutenberg’s printing press made it possible to issue the first scientific journal, analogously the Internet created the technical opportunity for Open Access to emerge and slowly become a part of the mainstream of scientific publishing.
Open Access is popular because being popular matters. We can imagine that when one spends a lot of time and energy on research, thinking and writing, there is a desire to share the results as widely as possible. Also many of the funding organizations, universities, national councils and associations use popularity indicators to rate the value of the scientific work and academic posts that they support. The main indicator of popularity in the scientific field today is citation level, which is increased, as much research shows, by the positive contribution of open access publishing. It is almost certain that free, on-line access to articles increases the number of citations in comparison to toll-access articles published in the same journal . What is more, self-archiving of e-print is very likely to have a positive effect as well. Research shows further that the majority of papers published in several prestigious journals received first citation before publication date. Moreover, looking more closely at these journals, the articles that were archived on-line, achieved on average more citations within 2 years than those that were not archived. 
So, self-archiving before publication increases popularity. Many researchers publish their working notes, database sets, drafts of papers or book chapters on-line to discuss results and methods with a broad group of specialists ahead of publication. At least one book has been written completely with on-line editor. This tool gives an opportunity to follow a process of creation in real time and discuss every current author’s thought before the work is completed. As Shauna Gordon-McKeon noticed a few days ago the open process of doing research allows ‘increased collaboration and dissemination of ideas, transparency leading to more frequent error checking, improved reproducibility, easier meta-analysis, and greater diversity in participation.’
The visibility of an article can be increased after publication by submitting it to popular websites. Open Access is also likely to have a great positive effect on popularity among non-scientific groups. A free, on-line copy of your paper gives your colleagues or business partners an easier way to become familiar with your work. Moreover, this can make you more recognizable to students and non-professionals. It is wise to consider all of this before signing a contract with a publisher. The ideal solution is to choose a publisher that uses Creative Commons licenses or similar.
Although Open Access popularity has reached a tipping point, there are still a lot of people who are skeptical about the model and consider it to be a less desirable option. The main reason for this is due to the various ways of measuring popularity. We live under the rule (some authors even refer to it as terror) of one dominant measure – the Impact Factor (IF), which is credited to a journal – not to an article. So, the points necessary to receive grants, awards or tenure depend sometimes on the names of the journals you publish in, and less on the strength and influence of your ideas, i.e. on your real impact. One may conclude, that since the IF measures journal citation level and OA has positive impact on citation, then the IF of an OA journal should grow successively, and this is right! I am certain that further research will prove this. Now the current problem is that many established, prestigious journals, which gained strong positions some time ago, are tollaccess, while the majority of OA journals are young (even though some of them have renowned editors and are backed by well-known institutions). There are some exceptions, but switching a journal from a subscription model to Open Access is not an easy task, so it will take some time until a major share of well-known journals go that way. The process of gaining a strong position is also slow and it is a big challenge for the editorial teams of OA journals to gain high IF.
Sometimes the decision of whether to publish in a prestigious tollaccess journal or in a new OA journal with a lower impact factor is hard one, but even then it is worth remembering the advantages mentioned above. Fortunately, not everyone has to make such decisions, since a growing number of well-known OA journals already have significant IF, and not everyone is forced to chase ‘points” by publishing in high IF journals. If you are one of these lucky people, I recommend you publish your results in an OA journal – maybe your work will increase the journal’s IF, and as a result you will be helping your colleagues. On a final note, we should be reminded that, as Michael Eisen claimed ‘the biggest problem in science communication today is the disproportionate value we place on where papers are published when assessing the validity and import of a work of science, and the contribution of its authors’.