I was only 2 when Airmiles started so i'm afraid your knowledge on that would be better than mine
I joined in 2006 when taxes etc still had to be paid, true they've done their calculations a little wrong for some places, if you're going to ask people to pay then really you should be asking for less points to be redeemed on all routes

I also collect both Airmiles and BA miles and understand that after November 16th when they all become Avios (the currency) i could move my avios from my "Airmiles" account to my BAEC account, i'm a little unsure about whether it'll still be worth having both accounts