Check the MapSetupDef.xml in Crusade folder. You will see the difference between Common and Abundant habitable planet is quite significant. IIRC, It been changed that if you not using Abundant, you likely to not get any planet or habitable planet at all. This also depended with Stars frequency since planets will spawn with star.

There is only three options in my experience. Not having any. Not having enough. And having way too darn many, cluster the entire map. There is no inbetween in each settings. I just go with abundant planets, habitable planets, and extreme planets but reduce stars frequency instead. It seem to normalize itself that way.

You can choose the how stars,  how many planets over all, how many habitable planets and how many extreme planets. Every point has ( I think) 4 possibilitys. In combination that's a lot! But every combination ( ever on excessive map size) creates one of the two extremes ! Habitable planets goes against zero or you have a unbelievable mass of. 

No matter what values are in the tables you are not able to say which settings creates which galaxy... 

I know this was discussed many times but I don't remember that the devs something say about that problem. 

The last statement was they want realize much more galaxy setting options you can choose from... But how should that works if the current one do what they want and not what they should. 

In the future you need days to find a setting you like before you are able to start a real game.... 

I'm "green" to much of this, so please forgive a possibly naive question. Just looking to learn.

With a complaint/"problem" such as this, why don't people simply alter the relevant xml files?