Though, as mentioned many times, morale isn't really that important anyway...
I question this statement.
I did an optimization exercise a little while back, and found that on a Q12 planet building an approval building first (to get to 100%) was the best building you could build to optimize a research planet. Not a hospital, not a factory, approval was the best.
Approval increases your base production and growth. That means you get your population quicker, and build buildings faster. You also get some influence as well, but that its not really pertinent to the discussion.
Population is also stronger now than it was in previous versions, so those factors are stronger than they used to be.
Now once your planets all mature approval may become less important. But during the main growth stages of your colonies, its a solid bonus.