1) Automatically flushing toilets. Because the most basic aspect of sanitation eludes us, 100+ years later.
2) Escalators. I actually don't think these things improve human traffic as much as people assume. Aside from very long staircases, I suspect we could all do just fine without them. (They aren't even useful for people in wheelchairs or parents with strollers.)
3) These things. Because our laziness knows no bounds.
"HOW ME EAT NOODLES BEFORE THIS?"