I think it would make sense if it basically augments natural healing abilities in carbon-based life forms. You make a good point about disease - bacta would repair the damage but not actually destroy what's causing the problem. So bacta is actually more an augmentation than a cure.

I love the idea of conspiracy theories around bacta. They'd be pretty believable given the overall power culture in the SW universe.

I wonder if there are people who refuse bacta on moral grounds because it's used as an excuse to hinder medical research? The introduction of bacta to the market must have desperately undermined a lot of medical research institutions, down through local clinics. Your miracle cure? Actually a supporting element of your dystopia