Controlling hundreds of motors using an arduino uno
Whatever MCU you use, it is unlikely to have 576 available GPIO pins.
One approach would be to devote 10 pins (one byte plus two control pins) and use 72 74HC595 shift registers (plus one driver per motor, of course). You could update the matrix with 72 clock cycles, bit-banged, and then update all the motor controls simultaneously with a single clock edge.
Whether the UNO is fast enough to do anything usable with that amount of data per update is another question, but update speed is probably usable.
Another approach would be to daisy-chain all 72 shift registers and use a single data pin, which would allow use of on-chip SPI hardware. With the addition of buffers you should be able to get the clock frequency up into the MHz range, so again millisecond-range updates could be possible, with only 3 pins (but getting it to work reliably might be a bit trickier).
In either case, excellent and well-thought-out circuit layout is essential. Turning on 576 motors simultaneously (with the associated surge looking more like 10x that) has potential to cause vexing issues.