Apple didn’t sue Samsung because they had a touchscreen phone. They didn’t sue because of rounded rectangles. They didn’t sue because of icons arranged in a grid.
Palm added all those together to get WebOS, which was easily distinguishable from iOS.
Microsoft added all those together (save rounded corners) to get Windows Phone 7, which was easily distinguishable from iOS.
Google added all those together and made the Nexus series of Android-powered phones that were easily distinguishable from iOS-powered iPhones.
Samsung added all those things together and arranged them to be as similar to the iPhone as possible. They ignored advice from Google warning them not to do so. Instead of pouring creative effort into improving on what iOS had to offer, they focused on copying what iOS had to offer.
That is why Apple took then to court, and that is why they lost.