The original post was made out of curiosity as I thought there must be a logical explanation - I understand the principles of trim, but was just surprised how sensitive aircraft can be.
Trislander, as a regular pax I often sympathise with the attitutes of fellow pax towards the CC as too many treat the CC as second class citizens. On the last incident of moving pax around, this was taken in good humour, but previously I have seen arrogant businessmen treat CC with utter contempt - a disgraceful attitute from so-called professionals.
The main arguments I have seen usually centre around the amount/size of cabin baggage. I understand that airlines have rules/regulations for good reason, and it amazes me why other pax cannot see this when arguing about issues that could compromise their own (and my) safety. particularly when the pax are breaking the airlines rules.
Incidentally I once saw a captain from another airline travelling as pax on BMI with hand baggage on the floor of front row seat arguing with the CC that he need not move it - the CC handled the matter firmly and diplomatically and won despite severe belittling from the captain (who ought to know better).