I can't speak to what might be in the head of an individual judge for an individual case. The reasons may have varied between those cases. Suffice it to say, my view is that the mandatory minimum should be upheld, with the exception of cases where it would be grossly disproportionate.
One of the changes that's being proposed in this legislation will help address the problem you've raised by saying that if you're going to deviate, you have to explain why. If you offer reasons as to why it would be grossly disproportionate or why society would be outraged, I can understand why you might see someone moving away. In an exercise of transparency, this bill is going to not only restore the mandatory minimums, but also give more clarity on the kinds of cases you've just raised with me.