Then you haven't been playing right. It is possible to have a high population with high morale in GalCiv2.
How many planets with a population of 32b+ and a high approval did you have in TotA?
I can honestly say, that it's not that easy to achieve. Especially, if you also want to run a decent tax rate. Once your population reaches 25b, your base approval will be at 10%, which means, that your morale bonuses from planetary improvements and your racial ability will only be 10% as effective (e.g., a 100% bonus will now only apply 10%).
There are only two races in the game, that could realistically manage that, while still making money from those worlds: the Torians and the Yor. However, to do that, both need planets with a PQ (40+) that is unrealistic to find.