It's funny how their replacement are consistently worse than what they replaced. You mentioned Google Chat, which was pretty great, followed by Hangouts which I'd still very good (arguably the best one out there that still exists), but succeeded by something that had no redeeming qualities at all.
Then we have Picasa which was succeeded by Photos. I like to be able to sort my photos, thanks.
Google Plus still doesn't have a public API.
Do you remember when it was possible to compile an Android application in seconds? Before you had to spend 30 seconds for Gradle to do absolutely nothing?
And Google reader was replaced by, well whatever they want you to use instead is not something I want to use.