I won't go so far as to say that academic research was completely open in the past, but it was more open (or, at least, affordable) before big publishers took over the publishing of journals in the 1960s and 1970s. Prior to that most journals were published by non-profit, scholarly societies. Nowadays, a handful of publishers account for approximately 45% of the journal articles published (I'm going from memory with that number, so don't quote me on it). The publishers, obviously, have more interest in turning a profit than the academic societies did.
You're right. Thanks for pointing that out.
Ginny, could you please fix that?