"I think that is slightly unfair one day you might need two seats together."
Sorry, I don't think this is at all unfair. I am organized and make sure I either have status, pay for seating, or check in online early to secure seats together - if other passengers are less organized they should live with the consequences, not me.
I wouldn't take this line for parents travelling with children (but, guess what, BA automatically allocates those seats together), but the idea that it's "OK" to kick one of your frequent flyers out of their preferred seat because some couple who couldn't get their lives organized can't sit apart for an overnight flight is ridiculous - not my problem! BA need to toughen up on this, it's seriously annoying.