Generally, copyright holders don't like it. Some even pursued RG to court. RG said they didn't upload the items, it was the authors. IE their defence is that the individual authors were to blame. And yet RG continually suggests you do upload copyrighted items. Disgraceful!
You need the copyright owners consent. Ask them for it. If they so no, don't do it. Potential readers must then get copies from the copyright holder directly.
I think the problem here is that publishers are exploiting researchers work without pay, and deny citizens right to access the knowledge supported by their own money (the research institutions are paid by the taxpayers money, and yet every taxpayer has to pay the price of the article , which is twice). Those who are reviewing the papers are not paid either, so how come that publishers are so succesfull in commercialization of other people work? The state is allowing it. But let's not forget that many legal things were and are not ethical at all. One can send preprint document, or the version which is not final, but stil, I think that open platform would be the only solution for this. The aim is that anyone can access the knowledge. I wonder how overly optimistic is this.
Distribution od copyrighted material might easily get you into trouble.
Your own material: If it is your own material, you can do with it what you want, unless a contract with a publisher says otherwise. Usually copyright stays with the creator, but distribution right often is handed to a publisher for a certain period of time. Acting against contract conditions is a violation of contract and you might be taken to court.
The calculation of the publisher is based on the condition of the contract. They have to make a living. If you have signed that contract you are bound to it. If you don't like it, don't sign it. There are many self-publishers out there. You don't have to be with a publisher. If you follow that path it is on you whether you want to sell e-books or distribute them for free.
Other people's material: If you freely distribute material written by an author other than yourself, you are violating said author's rights and you might get sued for that. If said author has signed a contract with a publisher according to which he hands over distribution rights to the publisher for a specific period of time, that publisher might be at your heels and sue you on behalf of his and his author's.
Let's be plain here: giving away something for free that is not yours is stealing.
Publically financed: There has been mentioned that research results and essays and books based on it are publically financed and should therefore be freely accessible to anyone. Not all research has been publically financed. Many PhD students finance themselves, or work on a 50% position and work on their thesis on side. Many researchers produce essays in their spare time and especially free researchers have to produce constantly to make themselves known.
Free knowledge: Also the argument "knowledge is free" - no, it is not. Knowledge derives from hard work of researchers who have worked on it. It is the fruit of their labor. People are readily willing to pay for a new car or any other item, so why should one expect researchers to give away their products for free? Give away their hard earned fruits of labor? It is this kind of thinking that leads those who plan a conference to invite speakers without offering proper payment. They argue, that researchers are employed at a public institution and therefore get paid anyway. Well, they'd have to take one or two days off for starters and this argument would only make sense if they'd be willing to pay those contributors who are not employed with a public institution and actually have to finance their living with public speaking and by publishing essays. They don't. The main argument to refuse payment: "You want to make yourself know!" or "It is a perfect opportunity for networking!" At the same time, they ask for entrance fees from people who want to attend a presentation.
To conclude this: What you do with your own essays or reserach results it on you. Whether you sign a contract or not is up to you. If, however, you have signed a contract, violating it comes at a price. As for other people's research and essays: the way they distribute it is totally up to them. General assumptions that lead to the conclusion "all research is free" does lead astray, since the conditions of each researcher are different.