It is that feature, but for the dashboard to visualise it.
As of 1.9.1 the feature to log all request data is available in the gateway, so you can get that now.
If you are adventurous and want to log to disk, take a look at Tyk Pump, which has a CSV exporter.
Note - you will need to switch off purging in your Tyk node for the Pump to work.
You will also need to compile Pump yourself 
It will be part of a future release as an installable package.