Translation:People want more liberty and equality.
Does the abstract always have -eco? For example, kuraĝa means brave, but is courage kuraĝo aŭ kuraĝeco?
Good question, but I think it is not always. This also falls in the question (imagine creating the language): will all roots be nominal or verbal? What is the intrinsic nature of the concept? What did come first?
When you derive an abstract quality from an adjective (kuraĝa) you can just change the -a to -o; it's more or less the same as kuraĝeco. But if it's not an adjective (homo → homeco / human → humanness) the -eco suffix is needed.
Well if you think of freedom as a complex consisting of several (independent) 'freedoms' then yes - f.e. you can say: freedom as a total contains having freedom of speech AND freedom of religion, if you only have one of them you're just partly free and therefore aiming for more freedom.