I am using Nova Launcher with my Tab because of my Touchwiz acting up. Copy/paste has never been a problem for me. My sister has the same model, is using Touchwiz, and copy/pastes just fine. My friend has the newer Tab 10.1 Note and has no trouble with copy/paste using Touchwiz, although she may have Jellybean. If there's a universal problem with Samsung devices, we don't see it. Why don't you try a different launcher and see if that helps. I use Nova Launcher and like it a lot.