On the gripping hand.
Slaughterhouse is plainly bad law and bad law, from a logical, historical and moral sense, does not deserve the respect of stare decicis. Overturning it wouldn't necessarily create any problems going forward. Despite the bare fears that raised their heads, it's pretty clear P&I is not a blank check (or at least need not be) for "any right one can imagine", which Gura made clear in his brief.
The Court had a chance to make history and clean up one of their most shameful messes. They chose expediency and timidity in simply ignoring it.
Either way, incorporation was, from most accounts, a slam dunk via due process regardless, why not ask for the moon?