It's really hard to say that they would be better with Datsyuk or Zetterberg, my point being that since we don't have access to a world where Z and D were healthy, it's impossible to say that the team would be in a better position or not.
That's like saying it's impossible to say whether life without one of your arms would be good or bad because it hasn't happened. Sure, but you can speculate with a pretty high degree of logical validity. Datsyuk and Zetterberg are two of the best players in the world. It's always better to have them than not have them...just like both your arms.