Google official blogs don't have a user comments section. Why?
warp: For every place where user-generated content exists, you need people to police things.  If you have a community, this can be crowd-sourced to some extent, but on a blog it is usually the blogger him/herself taking up that task.  This is not a very fun way to spend your time, it's not particularly productive.  The internet already has enough forums.Also, I expect google is big enough that any feedback they need to know about will bubble up in various places around the net where some person at google will find it.