I'd guess some people want to keep a bit of the momentum going for fuel efficiency? Going from standstill to moving, with a big heavy metal box, requires more energy than simply accelerating an already existing momentum, even if it's just a small momentum.

But I'm with you: Stop means stop

Many stop signs are placed such that stopping for them prevents you from safely observing oncoming traffic. So after stopping at a stop sign you still need to slowly inch forward checking that the path is clear making the stopping portion of the exercise absolutely pointless.

Further my habit of actually stopping has gotten me rear ended and tossed into an intersection. Doing things unexpected can be very hazardous.

Yup, but you still are supposed to, you know, "STOP". :) And isn't it done on purpose? This way, you are not breaking the knees of pedestrians that are crossing the road & you are not sending bicyclists flying. Stop, slowly inch forward (no broken knees, no flying people), enter the road when safe. I'm always wary when walking across the road with a stop sign, precisely because people don't stop at the line.

It's a shame that following signs is unexpected. Somehow, it's not acceptable to run a red light because "no-one is around anyway", but it's fine to do rolling stops?