Frequent flyer programmes are not as good as they used to be.
Do they generate loyalty? I think they do.
I used to have a BA gold card 15 years ago and I felt I was treated like someone special.
I changed to KLM because BA are not interested in flights outside fortress Heathrow, so KLM and Schipol are much better with connections from most UK airports.
KLM obviously thought loyalty programmes were very important.
The result was, it became too easy to have a card for lounge access.
It became ridiculas. The KLM lounges at Schipol had elite? travellers packed in like sardines. It became more elitest not to uses the lounges.
I have a Patinum card for life, so no need to rack up the points but airmiles are nice to collect.
I still use KLM when possible, I like them. I dont like KLM UK Cityhopper.
They are not so professional as mainline.
Your chances of a free upgrade, absolute zero.
To them pax are pax.
In my view the biggest plus for being a card holder, is priority check-in.
I think though that generally because fares are very low, probably on a par with locos in most cases. For this reason, you no longer have the luxury of lounge access when not flying with KLM. In the old days you did.
However,in the final analysis, I think they do bring in extra pax.
Especially for those whose fares are paid for by the taxpayer.