Bostrom and Sandberg (in your linked paper) suggest three reasons why we might want to change the design that evolution gave us:

• Changed tradeoffs. We no longer live in the ancestral environment.
• Value discordance. Evolution's goal may not match our own.
• Evolutionary restrictions. We might have tools that were not available to evolution.

On #2, I'll note that evolution designed humans as temporary vessels, for the goal of propagating genes. Not, for example, for the goal of making you happy. You may prefer to hijack evolution's design, in service of your own goals, rather than in service of your gene's reproduction.

Lots of evolution's adaptations (including many of the biases we discuss) are good for the propagation of the genes, at the cost of being bad for the individual human who suffers the bias. A self-aware human may wish to choose to reverse that tradeoff.