Yes, I think there's a balance we need to strike here. Being excessively rude and tough can demotivate employees and decrease productivity, but being too nice and polite won't get the message across.
I agree with finding a balance. A blunt attack may knock one person's confidence causing them to no longer offer ideas while for another it may encourage them to think a little harder about the problem before offering a solution.
Excessively tough-minded bluntness is frowned upon for good reason.