Yes, you do because what you are writing now is very different to what you wrote before. You first started to say that it was all about convenience and price. When I objected that FFPs do matter, you then added that they mattered for luggage allowance. When I objected to that, you then said, that it is about something else.
Indeed. This is precisely what it feels like: that you look at this with very heavily North America-tinted glasses.

Not on light fares, they don't. Status will not increase your luggage allowance from 0 to 1 on BA. It will only increase it from 1 to 2, 2 to 3 or 3 to 4. I would have thought that the main discomfort with luggage fees (even in the US), is not so much on having to pay for a second, third or fourth piece of baggage. It is about having to pay for the first one and, on this, status will not help with you BA.
I think that we can all agree with that (even if some will argue that there is also a psychological element about caressing the ego of FFers, etc..., which you can really see in the rhetoric being used by airlines to give the sentiment to flyers that they are 'special' even if there are thousands of persons who are just as 'special' as them) but it does not follow from this that FFers routinely make cold, rational calculated decisions and that their membership of an FFP is a result of those calculations. We all make heuristic shortcuts in our decision-making and membership of an FFP is no different. We reckon that the package of benefits provided by the FFP sounds about right for the price we pay. We don't do detailed calculation as to whether buying tickets without being member of the FFP and paying for a few extras would be cheaper. We just form a global picture as to the price paid for the overall product (in terms of spend but also other requirements, having to fly on X airline rather than Y, taking this routing rather than that routing) is broadly OK. In making that determination, our view will also be swayed by our perception of the worth of the product and branding will play a significant role in that (to different degrees on different people of course, like all advertising). Once we have made that determination, however, we do not recalculate on every occasion.
What an event like this does is to significantly raise the price of the product in a sudden manner, and therefore make us re-evaluate whether it is worth it or not and some will start to think at that point that the emperor has no clothes, that the product is in fact not quite as good as they had grown to think and therefore look elsewhere to see whether there is better to be offered on the shelves. There may or may not be better products on the shelves and I would agree that, for London-based flyers at least, BA will still remain a sensible choice, albeit one made without the enthusiasm that they might have had in the past. But for some, it won't and/or it will be one of several possible options worth looking at, either globally (and therefore prompting a shift in FFP membership) or on an ad hoc basis (butterflying on different airlines regardless of FFP membership). How many are in the latter camp, god knows. BA assumes that that number is acceptable but they don't really know and it is possible that they may be under-estimating this, in the same way as FFers may be over-estimating it. Our cognitive biases will tend to colour our judgment here and I would agree with you that FFers will have a tendency to over-estimate the significance of FFPs in decision-making and to generalise their own feelings as if they were universal. But, ultimately, this is something of a jump into the unknown.