“A kesuba protects marriage and the wife by making divorce harder and more costly to divorce her. The prenup does the opposite by making marriage more expendable and easier to dissolve in divorce while making it more costly to stay married.”
That is completely false in our times; in fact it is almost the opposite that is true. The ketubah is not enforceable in any court, at least in galut. The prenup is the only protection a woman has against a husband divorcing her in secular court and leaving her a penniless agunah. No prenup makes marriage more expendable; the prenup requires a husband to act responsibly.