I have 500,000 miles and can never ever use them
They are getting useful for last minute flights within Europe. Just rough figures, so don't try and pick them too pieces because if you do you are missing my point, but when booking a week in advance..... Loco might be after £125 one way and BA £200 one way. However you still find good availability when using BA miles, and they still stick it to you with their deceptive fuel surcharge, but total cash price for late bookings now tends to be less than the locos.
Never used to be like that, but the BA fuel surcharge is dropping and the LoCos are getting more expensive. .
And as for why they never contact frequent fliers, probably because they have already decided exactly what you want. They will probably also tell you that devaluing miles is what the customer wanted and they will have a specially designed questionairre to prove it.