The extreme planet frequency slider is a TA-only feature (and only as of 2.x).
Sadly, it didn't get backported to DA.
If you like, you can go into the raceconfig xmls of each of the races (to be fair-or just yours, if you're feeling mean) and set the five extreme colonization abilities (at the bottom) to 100.
Whether you put it as an inherent in the ability slot or as a points-costing ability is irrelevant, since it isn't an option and therefore doesn't cost points.
And since the game only recognizes 0, 50, and 100% values, even if you stack the techs on top of inherent abilities, or set your inherent abilities to greater than 100, it still doesn't mess anything up.
This will solve the issue for you for sandbox, but it will invalidate an MV game.