With a new interaction model, it often matters more to build the path to get people there, not the new local maxima itself (unless you're going to get kids to adopt it first, but Wave was definitely not targeted at them).
The Wave "onboarding" experience definitely should have had more demo videos, had features that turned on or were discoverable slowly, or had sandbox rooms where you could try it out with basic bots. It's a major missed opportunity that Google didn't do this; it feels to me like Google didn't have an internal playtesting or dogfooding culture where they intentionally left some people out so they could be fresh. I wrote about how to build this culture here: https://dustinfreeman.org/blog/playtest-rituals/