I had to look this up to confirm, but pigtailing isn't required. And seems like a PITA since that's even more wires in the box.
its smart to do. If you dont, you end up with your outlet being a series point of failure, when the outlet fails all downstream devices will as well, as well as all amperage draws in downstream devices having to pass through the outlet rather than through the rated wiring.
Yeah, it sucks from a wire fill perspective, but its the right thing to do.