Why will Obama be worse in this respect than FDR or LBJ?
In a vacuum he is not worse; he's probably only mildly dangerous by himself.
In fact, I seriously doubt he even has the capacity of either of those two. (And given LBJ's limited capacity, that's quite an assertion).
However, my fear is based on the position the United States is in today. He does not occur outside of history, he stands posed to push the US further into the socialism that his intellectual predecessors began. FDR began social programs that even though
we know are collapsing under the weight of their own promises, we cannot find the political will to scrap them. (I.e. medicare and social security)
Perhaps I should be more optimistic: I realize that these things
can be fixed, it's just that it seems it takes four years to screw up our country and 80 to undo the damage. (Alright, FDR had more than 4 years, but it only took 4 of his years to do most of the damage).
Maybe our citizens will wake up and clean house. Unfortunately, I see nothing in the history of republics/democracies to give me hope that the people will turn from voting themselves largesse from the public coffers.