Cal, healthcare reform is still under construction, and Dr. Carson is more than qualified to give his perspective. So those comments were not inappropriate.
On taxes, sure, we know the criticisms hit home. But Dr. Carson did not criticize any specific policies of the president. Or has Obama actually said he favors punishing wealthy people? (we know he does, but has he SAID it?) No.
So the only reason the comments could be deemed "inappropriate is because we all know what the president believes even though he doesn't admit it publicly. That is the presidents problem, not Dr. Carson's.