Here's what I did.

I opened the brake fluid cap to ease the pressure when using a C-clamp to compress the pistons. Put new rotors & pads on (pads were Wagner Thermo-Quiet). Tightened brake fluid cap. Drove car. Forgot to tighten rear left lug nuts, so... did that.

Now... the brakes are certainly quiet, but the pedal feels slightly spongy.

Wondering if bleeding is really necessary after a basic replacement of pads & rotors. . . .

 

Bleeding is generally not needed after pads/rotors change. Did you add any fluid?

If you don't know when the fluid was last changed, now's as good a time as ever to do it.

 

Just top it up with DOT 4 fluid. IIRC DOT 3 or 4 whatever the owner's manual says.

I did the rear pads, compressed the rear pistons without opening the cap.

 

After driving it a bit more, I guess it seems fine.

It must just be the feel of BRAND NEW brakes/rotors. I guess I've never felt that before.