The obvious, tedious comparison to make is with Apple, which chose to ditch "Computer" from its name way back in 2007. It was the moment that the company signposted that the iPod wasn't simply a fluke and that it saw its future in consumer electronics. After all, the change was announced on the same day that it announced the first generation iPhone.
Last summer, Elon Musk unveiled the second part of Tesla's grand master plan for his transportation business. The document included merging the energy generation and storage businesses he was involved with, as well as widening Tesla's vehicle portfolio. But beyond that, Musk wants to build super-safe autonomous vehicles and enable people to rent those cars out when they're not in use.
All of that would turn Tesla into a conglomerate with divisions in car and battery production, energy generation, artificial intelligence and an Uber-style transportation marketplace. You can see why anyone would think having Motors in the name would feel a bit like a straitjacket.