They already don't earn enough from First Class AC coaches, it has mostly been just for rich folks maybe tourists. Also, if we think about installing showers etc, we should also be concerned about the sanitation conditions outside the train, which aren't ideal and, the sanitation of the water used in trains, which many don't trust. But I do agree atleast H1 or HA1 should be there for most high demand trains. Main contender for this coach is Kerala SF in my opinion. Also many NFR trains bound, especially most of the south bound weeklies, Brahmaputra Mail, to name a few, do not have HA1 for reasons that are not known. I'm sure the patronage would be good.