There are cases for quite serious readings of Engelbert Humperdinck’s 1893 opera “Hansel and Gretel,” which Los Angeles Opera has just opened at the Dorothy Chandler Pavilion in a revival of Doug Fitch’s 2006 production. In his program booklet essay “Hansel and Gretel” (“Fact and Fiction”) Basil De Pinto pointed out the opera’s very real concerns with hunger and poverty {…}