I didn't detect that assumption in this book. Legacy is listed as one of the four retirement goals. Annuities can support higher lifetime retirement spending than bonds alone, due to the mortality credits. So, a retiree worried about longevity risk and not concerned with leaving a legacy would tend to view lifetime income annuities more favorably, where a retiree who highly values leaving a legacy would tend to steer clear.
To paraphrase from my original post, the presentation is 'X has Y characteristics, which will appeal to folks who value Z.'