The point is simply to protect the term "doctor" in healthcare, which the public understands to mean MD/DO/dentists, the same as the RNs in every state have gotten legislation to make it illegal to identify yourself as an RN if you're not licensed as such. The proposed bill has nothing to do with practice. They are not "opposing" doctoral degrees for nurses; they just don't want people with those degrees to create any confusion about whether they're advanced practice nurses or physicians by going around calling themselves "Dr. So and So" in the clinical setting without being clear about their discipline/role. In the case of midlevel providers, "if it walks like a duck and quacks like a duck," that doesn't necessarily make it a duck! While I don't think this is organized medicine's finest hour, I don't have any problem with that basic idea. It's unfortunate that the term "doctor" has always been associated so strongly with physicians here in the US, when there are so many different kinds of people who have doctoral degrees, but that's the reality of the situation and it's not going to change any time soon.
I, as an advanced practice nurse myself, would have a v. serious problem with any non-MD/DO healthcare provider who presented her/himself to me as "Dr. (whomever)" without clarifying that s/he was not a physician.