One key reason to expand the number of liquor licenses in Boston is to invigorate neighborhoods outside the city’s traditional core. Hamersley’s Bistro, now a celebrated South End institution, has shown just how powerful an engine of redevelopment restaurants can be. Owners Gordon and Fiona Hamersley, who announced recently that they’re closing up shop later this year, have won ample praise for their farm-to-table food and their establishment’s casual elegance. But when they opened up on Tremont Street in 1987, they were also betting big on a South End that still had a gritty reputation. They and a few other restaurateurs provided an important urban amenity: a place for nearby residents to have a pleasant dinner, a reason for outsiders to come visit. In the years since, the South End has emerged as one of the city’s major dining destinations — with the real estate prices to show for it. But today’s Boston has a new set of dreamers who are ready to try their luck in a different set of emerging neighborhoods. They deserve the same opportunity the Hamersleys had.