You'll need them.

I'm not up on the specs that USB power provides, but a typical LED needs ~3vdc to light. You're talking nearly 600
LED's here.

At the bare minimum, you'll need resistors in place to drop
the voltage down to something the LED's can use since it's unlikely the USB port is going to natively provide a perfect
3VDC source

Amp draw should be looked at as well. While LED's don't consume a lot of it, you're talking about an insane number
of LED's. How many at a given time are going to light ?

If their draw exceeds what the USB port can provide, well
I have some bad news