the spam problem advantages google, as your own story illustrates, so it's unlikely they'd really want to help solve deliverability/spam issues systemicly. making personal email hosting more difficult means they have a chance to capture your email data streams via gmail. whether you switch there or not, it creates a pressure for most to aggregate on gmail, which means they can see most email exchanges.
For sure. Good spam filtering was one big reason for people to switch to GMail. And a lot of people who gave up hosting their own email have switched to Gmail as well. I'm sure this doesn't rise to the level of conspiracy, but there's little incentive for them to fix the broader problems.
