Why should society want to combat this at all? Or why should each of us want to combat the decline in ourselves (to whatever extent we have such creative ability)?

Eliezer gave one possible answer for the first question above, but you might be right that delegation is better for society as a whole.

As for the second question though, individuals capable of paradigm-busting innovation will probably do almost anything to keep those creative powers, because instances of successful or partially successful application of those powers in the past have probably been high points of their life.