> the reason it has been limited to those cases is drug development, today, is constrained by commercialization.

That's a good observation, but I think it's an incomplete picture. Another important constraint is often regulatory inertia and historical baggage.

The UK pioneered small classical and adaptive trials using Bayesian methods, and there were some promising results. A lot of modern Bayesian methodology was, in fact, developed at the MRC BSU Cambridge with this goal in mind. For example, the probabilistic programming language BUGS (1989).

Given that most drugs fail, the industry is highly incentivized to use Bayesian methods to fail faster. These models allow for more rapid dose-finding and the ability to distinguish promising leads using interim data, which is vital given the massive cost of any trial, especially late-stage failures.

But for Bayesian methods to make a dent, they'd need to be applied to a large number of trials, and change doesn't happen overnight. Lots of big pharma players, e.g. GSK, are becoming interested in moving to Bayesian methods in order to leverage prior information and work better within small-data regimes.