Why did microsoft get sued and why isn't anyone suing apple?

Short answer: Because Microsoft was a monopoly and Apple is not.

Actually that's a lot of it. When microsoft was sued they had an overwhelming majority of the broswer share, and with IE being so tied into the OS of most computers sold, there was very little room for other browsers to maneuver.

I think the key word is Apple hasn't been sued _yet_. They are no where near as big as Microsoft was in the computing/browser market. So them ignoring flash isn't going to kill flash as there are plenty of other devices/os's etc that can and will use it.