There are people who live for theory, and others who can't stand it.
Those who live for it think that nothing can really be understood unless it is seen through a critical lens. This is so because our existing conditions of life cover over and obscure a set of interests that serve to marginalize and disadvantage many people. These conditions are regarded by the vast majority of people as just natural, inevitable, and therefore justified. Thus, the inequities in society become part of the structure of society itself.
All this comes from certain assumptions we inherited from the Enlightenment, assumptions such as the idea that there is progress in society, and that Western society is the pinnacle and final goal of all social progress.
Those who can't stand theory have some serious complaints.
First, the cynicism that a critical theoretical position assumes seems unsustainable in real life. After all, we get up in the morning, we love those close to us, we strive for a better world, we believe in things. These are all positive. Critical theory seems to have no place for these.
Second, critical theory has, for many, made the pleasure of the text impossible. It used to be that one could just enjoy culture; now we have to see through it, analyze it, stand back from it. Theory seems to require a "cool" stance, an uninvolved critical eye. To actually enjoy something seems naive.
Third, theory's appetite has, for many, been rapacious. It has devoured even good things in culture. It has made us question the greats of literature, like Shakespeare.
The result has been that there have been "culture wars" over the past decade or so. These are cast as the battles between the conservatives (e.g., William Bennett, Lynne Cheney, Allan Bloom) against the radicals (Stanley Fish, Derrida, etc.)