1. Well, if MBNA were claiming it was identical to BA's Amex card, I think you have a pretty good case to have a word with the Trading Standards Office. Did they advertise that, or is it in the promotional literature?
2. The use of 3rd parties is standard, but I agree this can leave nasty gaps in the communication of benefits. It also puts a lot of responsibility on the third party (ie, MBNA or Amex) to deliver the same customer experience as the airline. When MBNA took over the running of the Abbey National credit card, I was very disappointed with the customer service and their marketing techniques, so I don't have a lot of time for them as a company.
3. As I said, the BA Amex offer sounds like a good deal. I'd get one if it weren't for the fact I don't fly BA. If Virgin were to partner with Amex instead of MBNA, maybe I'd be interested.
4. This comes down to understanding the full T&C's before switching spending to take advantage of an offer. Most offers, whether they be from an airline or a supermarket have a catch. If you don't like the terms, no-one's forcing you to take advantage of the offer.
Pix