Wave's core ideas are at the heart of modern collaborative tools. It's just the UX that was poor. If they stuck at it and refined it, they could be the leader of this segment. Something that I can say for a lot of what Google does. They quit too fast and maybe more importantly they don't use the knowledge they got from their failures to improve.

It's the same with Inbox which remains the best email client I ever used but weirdly Gmail never got the core UX ideas which made it works so well. I would like to say Google doesn't get UX but clearly they have great UX designers on board. It's just that they probably never get final say and are not first class citizen.

For me, it's an issue of discipline. A lot of Google products seems to be built like R&D projects with the mindset which goes with it. They don't have the discipline to do the boring refining work that great UX requires.