This is old news - the new seating policy was introduced last October.
The full policy is here -
British Airways - Seating guide
As previously mentioned, it's still free to choose a seat. Simply do it at check in. If you want greater choice and flexibility with regard to where you sit, then there is now a small charge for the privilege.
To be honest, whilst it may seem like a total outrage, it's not. Particularly in comparison to, say, the restrictive baggage allowances to USA now. And BA need to get some pennies in the bank at the moment. Which would you prefer - a small charge to choose exactly where you sit, or that convenient flight you want to book not available because it's been taken off the schedule?
If you don't like it, then don't pay and wait till check in!