There is a reason Shakyamuni focused on dukha, and not sukha. That's because most people believe they are basically happy with moments of unhappiness. They believe that their sources of happiness are material things and giving in to sensory cravings, and it's only when these cravings aren't fulfilled that they become unhappy. It is very difficult to get them to see that what they are doing is actually creating their and other people's unease in life. I see the logic in changing the focus, I still disagree with it. Buddhadharma shouldn't change to meet the approval of other religions. And the focus on happiness feels like the mutation of dharma from spiritual practice to pop self help, just more consumerism/materialism.