I'm all for being good to fellow humans, but as Spock said, the needs of the many outweigh the needs of the few.
You see it all the time on Wikipedia. "If only we banned [topic speaker doesn't care about] we could finally make some progress on [topic speaker does care about]." But it ignores how people really work.
If you yell at people doing something good, they're not going to go do the other good thing you want. They're correctly going to ignore you. If you force the issue, they'll leave. Or if they can't, they'll turn into perfunctory drones.
It's not like BA's spending some large amount of money on this. I see no additional expense at all. The people doing it are doing it out of love and compassion. There's no reason to think that this will prevent them from being loving and compassionate to others. If anything, it may help other travelers, in that these people are a) developing their capacity to care about their customers as people, and b) doing something that provides much-needed variety in a parade of hurried, anxious, grumpy, entitled customers.