I have written about this several times before.  Product development involves making a number of potentially costly trade-offs in parameters and specification.  The Aventador retains the same configuration as introduced with the Countach almost fifty years ago.  
 

The transmission is in front of the engine instead of behind as found in most rear mid-engine configurations. This means that the significantly wider and more squat dual clutch transmission can’t be utilized if cabin space is maintained. The converse, turning the powertrain around so the transmission is at the rear of the car, is an even more complex and costly option. Frankly, with the low production volume and onerous future regulations, this is not a cost effective solution either.  
 

Prediction: Lamborghini will maintain this configuration with corresponding modifications to the transmission, like the Sian’s hybrid system, until that V-12 is regulated away.