Why don't the door buttons (open/close) on the central line tube trains work?

Question

When the new trains were first introduced it was so handy to have the doors only open if there was someone at the platform waiting to get on. Especially at a time like now when the weather is cold and rainy outside.

Answer 1

The Guard now works them for you to ensure safe practise and help with time keeping

Answer 2

Because a certain percentage of passengers are not clever enough to work out the correlation of a button press and the door opening.  They just stand on the platform waiting for the door to open by itself.

Answer 3

Someone in LUL decided that all doors were to be opened at each station. I can't see things being reversed as the District line stock is having its door open buttons removed and plated over.

Certainly it was better on the quieter parts of the line where the loud 'chirp' didn't sound if all doors in a coach were already closed