What did the founder expect would happen when he sold the company. Obviously Microsoft wanted to remake a Wunderlist app to be apart of their Office 365 portfolio.

Why else would they have bought them

Microsoft paid more than 100 million dollars to kill this.

They didn't kill it, they did exactly what they promised to do: they converted it into an Outlook sub-brand tool that speaks Exchange first and everything else second. It's just unfortunate that it was harder to keep Wunderlist's "soul" than Accompli (Mail) or Sunrise (Calendar) in the conversion/brand and feature alignment, but also maybe not surprising because TODO features have always maybe been historically some of the weakest parts of Outlook.

What was so great about Wunderlist? For $100MM, I think the previous owner could build a new one... it's just a to-do list. If you built one for your school project, you'd probably get a C+ due to lack of originality and difficulty.

It's way easier than trying to use Outlook for that purpose. Tbh I don't even know how to share tasks in Outlook.

I think the only intesteing thing it was the community around it than the code itself.