Is there a legal obligation on my part to include my wife in a medical malpractice claim if I choose not to?

It's not really your choice, it's hers. Here's the reason: the law recognizes that with a married couple, when one is harmed, both are affected. The spouse who is affected indirectly has what is called a "derrivative" cause of action, as it derrives from the main party's cause of action. So, it isn't a "legal obligation" on your part, it's a right that she has as her own. Your wife can claim that she was adversely affected by the malpractice committed upon you. Of course, she will have to prove the extent to which she was affected. There are all sorts of permutations, so I can't go into all the possible scenarios here. Talk it over with your lawyer, if there is a possible conflict of interest, she might have to get her own lawyer.