All good points, but another thought has occured to me (yes I know, that's two this year already!)
Folks wear the poppy. Other than a show of support, sign of support or a badge of conformation, it serves another, possibly unintended purpose (or maybe not). Marketing, I guess. If people feel pressured into buying and wearing a poppy, they are pressured into donating to the RBL. Great, eh? Everyone's a winner.