A characteristically full and wide-ranging essay, correctly identifying the functionalist, Marxist and feminist perspectives. I have, as usual, made a number of changes to your ording.
I think the omission here is on the NATURE of the social control, which is particularly important in assessing the views of different sociologists.I therefore offer the following reflections:
The medical profession is the recognised authority on illness and treatment (for the reasons you give) and so it has established a monopoly on the official identification of sickness AND on the legitimate practice of healing. It also shapes ideas and expectations of how those who are pronounced sick may behave.
For Parsons, being sick is a 'specifically patterned social role' - and it is for this reason that medicine is a form of social control, which formally defines a person's condition as deviant, and then functions to control the deviant's behaviour. Being sick implies two RIGHTS - the sick person is temporarily exempt from his/her 'normal' social role; he/she is generally not held responsible for the condition, and so is not blamed. Being sick also implies two OBLIGATIONS - the sick person must see being sick as undesirable, and so has an obligation to do everything possible to get well; he/she is required to seek professional advice and to cooperate. The rights and obligations are mutually dependent.
So there are two underlying value themes here. VULNERABILITY - getting better is seen as not possible by individuals of their own accord, and so they must be treated and looked after. This, however, runs the risk of exploitation - since the techniques of healing may be physically invasive, while the relationship is by its nature unequal, and thus requires a high degree of trust. Then, DEVIANCE - the sick are a potential social threat aince there is a danger that they may simply be evading their responsibilities. So it is important to identify the GENUINELY sick, and it is in this respect that the medical profession acts as society's gatekeepers.
Interactionists thus argue that the whole doctor-patient relationship shapes the patient's sense of identity - often they move to a stigmatised status, and are the victims of labelling and stereoytping, both by professional medics and by society at large. Hence, or example, the physically impaired are often spoken to as if they were mentally impaired. In extreme cases, as in the former USSR, unacceptable political views frequently resulted in 'patients' being locked away in psychiatric hospitals.
Of course Parsons assumes that all individuals voluntarily accept the ascribed 'sick role', while in reality many have aversion to medical treatment (or even to visiting a GP); others cannot afford to spend time off work. Others may want to avoid the stigma that is attached to many conditions. Hence patients are certainly not all 'passive' and 'controlled'. Indeed, some may DISSENT - experienced, say, in absenteeism from work, which is then a reaction to attempted medical control. Increasing numbers of sick people, contrary to Parsons, ARE often held responsible for their illnesses, on account of lifestyle choices - often, obesity, heart disease, lung cancer,blood pressure, AIDS fall into this category. Chalfont and Kurtz (1971), for example, demonstrate that alcoholism is not generally accepted as a genuine sickness; similar research comes to the same conclusion about drug addiction and gambling. And Parsons entirely disregards CHRONIC illness, which does not fit his scheme of things at all.
In reality, the doctor-patient relationship shows significant variation, and not all patients are compliant, cooperative, submissive or 'socially controlled'. Parsons, like all functionalists, produces a taxonomy of 'control types'. In the case of paternalism, there is high doctor control and little or no patient input. In the mutuality case, both have knowledge, and so treatment is effectively negotiated. In the consumerist case, the patient has great knowledge of his/her rights, and often also of his/her medical condition; here the doctor assumes a more passive role. Cartwright (1967) found that 56% of GPs complained that their patients 'lacked humility'! Byrne and Long (1976) identified a range of doctor/patient 'communication styles', though found that the doctor-centred was prevalent.
The major source of control (and patient dissatisfaction for that matter) is the ability of doctors to restrict information. Johnson (1972) identifies a 'competence gap' between doctors and patients - the greater the gap, the greater is the doctor's dominance and the patient's dependence. Withholding of information also covers up doctors' own uncertainties about diagnosis or treatment, and - particularly in these days of litigation - minimises the patient's ability to evaluate the doctor's performance and to detect mistakes. Research shows that the middle classes receive longer consultations; they ask for and get more information; hence the competence gap is smaller. Doctors are far less likely to divulge information to working class patients. Women are also less happy with doctor-patient interaction, especially if the doctor is male. Szasz and Hollender argue that the main factor influencing the relationship (and thus the degree of control) is the severity of the disease/condition.
Context also affects the degree of control - doctors have far more power to impose conformity in hospitals, even to the point of giving people new identities as a result of the loss of patient control and the imposition of hospital routines. No essay would be complete without a reference to Goffman (1961) and his analysis of 'total institutions' - it is highly likely (especially wherever the condition is mental) that there will be a process of MORTIFICATION - i.e. a complete and imposed change of personality.(Read 'Asylums' - one of the great Sociology books!)
Finally there is the 'medicalisation of deviance' - the idea that deviant behaviour is DEFINED as sickness needing medical treatment. So who then does the defining? This links nicely with your points about Marxists.
I hope this is helpful.