The question is: how do you prove that something is not "fair" use? A statute, per-se, does not immediately make this an easier task (i.e. restricts fair use), or vice-versa. A statute establishes some criteria, and those criteria may be restrictive or not in the very same way that, under CL, a judicial interpretation may, or may not, establish new boundaries and new interpretations. The issue, at the end, boils down to: who has got the power to decide and rule?
I am afraid the answer always depends on the balance of the powers on the battlefield, and that balance tilted in the 1980s in a very clear direction. It did not tilt in the bad direction because SL took over CL, but because the political momentum (and the Reagan administration) pushed in that direction. The direction of change, until now at least, has kept steady and we are now in the situation we are. Until technological and economic changes will not tilt the opposite way (the same argument applies to patents) the current trend will persist because it is supported not by the majority of people but by the most organized and powerful lobbies.
That is the political problem. I am well aware I do not have an answer as to HOW we can tilt the political momentum in favor of free speech and against intellectual monopolies, but THAT is the problem we need to face. Free speech is a collateral damage(d) freedom in this battle, which is one of economic and social interests. Hence, it seems to me, the question we should ask is: how do you build and who can build a coalition of social and economic forces that will find intellectual and inventive freedom to be preferable to intellectual monopolies. At that point, either CL or SL may be useful to push back intellectual monopoly. I do not see, a-priori, why one system would yield better results than the other.