I love it when Magic revises old mechanics.
Most of the mistakes we see out of R&D are development errors: Thragtusk should have cost {3}{G}{G}, Pack Rat reduced variance unacceptably, the combination of Sphinx's Revelation and Supreme Verdict meant two years of control decks being only Azorius or Esper, etc. However, a reimagined mechanic is a broader admission that the original fell short. More importantly, it demonstrates how to improve a mechanic that didn't fly the first time.
