Most people who want tools are more concerned with things like transformer design, efficiency, ripple, etc... open loop parameters, basically. Most people don't think of stability as anything other than a yes/no question, so this program probably just spits out a foolproof stable feedback loop. Most people wouldn't be interested in bode plots or phase margins or whatever.
As for why, keep in mind that these manufacturer-provided programs generally exist to draw customers for the products they sell. You have to buy the hardware from them, but not the stability analysis, so they have no incentive to provide it.