It doesn't have to be "enormous" volumes of data (except by 8-bit MCU standards): you could also do lots of processing on small-ish volumes.
Or do "soft peripherals" a la Ubicom (recently merged into Qualcomm): they used multiple cores to bit-bang interfaces like Ethernet (and even SATA, according to one story I read recently), instead of making many models with different specialized "hard" peripherals.
Let's say you want to do something like the Ardupilot: dedicate a core to each servo and each input sensor, and you never need to worry about your elevators wobbling if another part of the system is busy normalizing a temperature reading or passing data to/from a distant central PC. And encrypting the data link so no one can hijack your UAV or steal the data you're collecting.
Similarly, for ground robots, you could create custom servo and motor speed controllers in software, with high-level commands like "move forward at 3.2 feet per second" or "wag the servo between 85 and 125 degrees with a period of 3.2 seconds".
64 cores is more than you'd need for the vast majority of hobby-level applications, but I could see even a relatively simple robot using 16 or more.