To me a complex hospital seems like something you would find in a well established city of thousands, not something you'd expect to find in a fortified frontier encampment of a few dozen. It just doesn't feel right. It is something I wouldn't expect to become available until you have a population of at least a couple hundred.
Also, the complex hospital depends on the idea of some sort of skilled healers, and perhaps medicines. If you don't have doctors you don't need doctor's offices, emergency rooms, surgical suites, and so on.
There are some currently useless items that could eventually become part of a more complicated medical system. Items like golden salve, spider venom and soap are just trade goods right now, they are not useful for anything. The Alchemist looks like a potentially useful noble, but all he's really good for is making soap. Since you probably won't get him until after you hit the lava, by the time you have the alchemist you probably don't need soap as a trade good. (I'm not going to burn a bunch of wood to make clear vials to build the alchemist's laboratory, a building that is only useful if I'm willing to burn more wood to make lye, not until everything else is under control anyway). The alchemist isn't that useful right now, but he has the potential to become useful in the future. The alchemist could convert cave spider venom to anti-venom, allowing you to treat those poor bastards that get bitten by a spider and spend the rest of their lives as narcoleptic. Or convert the venom (perhaps combined with another item) into an anesthetic, allowing even severely injured people to get to sleep (lack of sleep seems to be what drives them crazy). Having soap and anesthetic would greatly improve the chances of a surgeon being able to complete a complex surgery without killing his patient.
I'd make the requirements for a Physician Noble to already have the Alchemist Noble, and a population of at least 200. You aren't going to attract a top guy if all you have is a few dozen laborers living in a rough walled cave, you just aren't. His primary job is to start the health care system the way the Manager activates workshop management and the Bookkeeper starts the economy. Once the health care system is active, dwarfs will start having happy and unhappy thoughts about the state of health care in the fortress.
"The Baroness got her ingrown toenail looked at right away, meanwhile my son had to wait three weeks to get the arrow pulled out of his arm."
"Only three weeks? Lucky bastard. I've been waiting nearly a year for knee surgery."
I think it could be a great addition, eventually.
A simple infirmary could be added now. It is basically a modified barracks, reserved for the injured. It keeps them corralled in one place, which would be handy right away. Even without medicine and no more care than they get now, keeping the invalids together in a central location would make it easier to care for them. It could also serve as one of the stepping stones toward a more complex medical system.