If you want actual answers, they are:
Indexed shifting was resisted by a handful of riders because they didn't want rivals to hear them shifting to a high gear before attacking/going for the finish line.
Clipless pedals were adopted with virtually no pushback. Not the first Look models, which needed a hand lever to unfasten them - they weren't real clipless pedals as we know them. Trackies still use (double) clips and straps for some events involving sprinting, as feet can pull out of clipless pedals when you're putting down 2000W of anaerobic power.
Disc brakes weigh more, make wheel changes more difficult as they can rub, and the UCI thought they could be sharp in the event of a crash.