Anyone annoyed that the Nikon D5100 camera will NOT autofocus with some Nikon lenses?

Nothing could be further from the truth.

Canon had the vision to understand that the future was  electronic control of both aperture and focus, and they needed a system that was able to accommodate that. They realised they would be struggling to do that with the then existing FD mount. They did take a big risk. They started with a clean sheet of paper and produced a "future proof" mount. Professional photographers immediately embraced the idea, and eventually, so did the consumers.

Technically the EF mount is much superior to the F mount in its accuracy of aperture control. Nikon are still having lots of problems with selling the idea of their very sloppy aperture control to pros who need very fine control. They made the decision of sticking with the F mount a keep supporting legacy lenses. They also took a risk, but it has turned out to be OK for them too.

I think Nikon is the last company that could be accused of forcing people to throw their old stuff away.

This is a totally unsupported view. You seem to carry a chip on the shoulder.

Whatever floats your boat...

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Cheers,
Peter Jonas