And maybe because even Google thought that their tablets were too much like Apple's tablets. http://allthingsd.com/20120725/apple-google-warned-samsung-a...
And maybe because their stores look like Apple Stores, their chargers look like Apple chargers, their Ultrabooks look like Macbook Airs, and some of their phones look like iPhones.
Apple never went against Palm, nor Microsoft, nor any other manufacturer, simply because these devices were distinctly different than Apple's products. And yes, I know that the case verdict was only about some specific patents (and no, these didn't include rounded corners), but it's probably clear that the decision of the jury was also influenced by things like the above.
You see, even if, technically, the patent system is a mess, and technically the verdict is therefore wrong (which I don't think), Samsung are still copycats. They're not the good guy, just because they use Android. Instead, they're just a capitalist company like Apple.