Colorado’s Central City Opera is a terrific company. But it is neglected when discussions of great American opera companies come up. “The perplexing question is: Why? It certainly is not because of any lack in production quality. The diversity and daring of Central City’s programming easily competes with any summer festival in the country. Part of the problem lies with geography. The company is not only a bit isolated, it is also a long way from either of the two coasts, where nearly all the major classical-music critics live. And travel budgets are being cut everywhere.”