For one, the Warriors signing Cousins was strictly a "rich getting richer" situation. He could not play a single minute for them and they would still be the favorites to win the le, and they don't need him enough to lean on him if things don't go well.
Secondly, the 2003 Lakers didn't have 4 All-Stars (5 if Cousins does actually get healthy) and a full bench, and the 2011 Heat were in their first year after a complete overhaul.
Lastly, Lebron, 4 boneheads, and a bunch of kids aren't beating the Warriors. The Cavs at least had a 2nd All-Star in Love...Who is Lebron's 2nd best player now? Ingram?
Personally, I think the Lakers will be closer to scraping for the playoffs than they will be challenging the champion unless Lebron orders up another mid-season trade package.