I think the main problem is that the articles and the suggestions this far are all quite complex for people to understand.
Now we here on FT are definitely not ‘average punters’ (or the ‘average Joe’ for our American friends). We here on FT are generally well versed in dissecting and understanding complex rules for loyalty schemes. But we are unusual. The beauty (if you can call it that) of the old mileage based scheme is that it was relatively simple to explain and for the average person to understand.

So therefore I think the most important aspect for any loyalty scheme is that it needs to be easy to understand. If not people will just not bother. Now we on FT might bother to grapple with complexity… but the average person (who is also the average BA customer) will not.