I remember how surprised I was when ransomware really took off, that victims would pay and actually get their data back. Sure, it makes sense, that criminals benefit in the long run if they truly return the data, but I was surprised that the criminals were actually that farsighted.
To me that suggests that rational economic forces really are at work and as a result, banning payments would cut back on ransomware attacks.
This is very similar to having a "we don't negotiate with bad guys" policy, which is common at least as rhetoric if not in fact.