RC:

Murcielago wasn't really a good name in my opinion, Aventador is much nicer. Gallardo is also quite nice, so I would keep it. At some point, they will run out of (nice) names.

Given the limited number of models Lamborghini has produced in its fifty years of existence, it is doubtful it will ever run out of suitable names.  

Lamborghini is as much about marketing as it is about engineering to produce super cars that, of course, is evident from looking at Audi's choice for CEO of Lamborghini, Stephan Winkelman and the image he conveys for the brand.  Using a new name for a new model gives Lamborghini increased press coverage, and hence, greater marketing presence with a limited outlay in funds.  If Lamborghini, for example, kept the name Gallardo for the new model, it would need to launch an expensive media campaign to promote the fact of a new model.  Now, with a name change, once the popular media sources cite the new name, there is some recognition of newness amongst the masses.