Does splitting spaghetti in half change the taste?
No, it's not true. It will not change the way they cook. Noodle cooking times vary by what they're made out of and by thickness, not by the length of the noodles.

The kids and I seem to prefer eating shorter noodles and dodging the hassle of spinning the noodles, but when there's company over we tend to do it the classic "right" way. No difference in taste.