Best of 2011 in pop music: Randall Roberts – With music so fragmented and the abidance of tip machines, the top 10 list has taken on a greater importance. Without it, the cacophony would be even greater. In 1977, writing on the death of Elvis Presley, Lester Bangs made a prediction that rings true when thinking about this year’s so-called best popular music. Wrestling with the disappearance of shared tastes amid wider cultural divides, the …