Here's just one: Even talking about posthuman psychological superhealth is morally frivolous. Another? Promoting superhappiness may lead to what one may call, informally, "inappropriate" behavioural responses.
Weak willpower & procrastination caused by dopamine hypofunction is one of those neurological deficiencies which effort alone can't overcome. Happily, in our transhuman paradise, even the most lethargic spirit can move mountains.