It's simple game theory, If i've been burnt by google shutting down something i've made part of my workflow or rely on (I'm sure most people at hacker news have been in this situation) I'm far less likely to adopt their next big idea.
They could have a division which puts these projects on life support or hell sells them to another company or even open source some of their products and let the community support them!
I'm still salty about google reader and their original podcast app on android among other things it would have been so easy to do right by their users.