Yes, how the human and AI "power curve" grows is important, but also (and possible more importantly so for low AIP games) their base values (where they "start") is also very important.
Hmm, so how can we encourage people to take more planets without making the very early game straight up "too much" harder in "normal" (not ultra-low AIP) strategies?
Maybe something like increase the "base" AI strength, but make the very first wave from the AI (for each AI player) be less than what the normal base scaling would imply. So the very first wave an AI player sends (aka, the first wave from AI 1 AND the first wave from AI 2) you would be around the same strength it is now, but after that, the increased "base" AI strength will kick in, putting you in more pressure if you don't try to get more resources after that very early stage, which usually doesn't happen in mid to high AIP strategies.
Then again, seeing how some maps make the very early game slow (ever been seeded next to high mark planets?), maybe it should be the first two waves.
Say, 1.5x the "base" AIP strength, but have the first wave (per AI player) be about 66.7% strength (which would bring it about to the level it is now), and the second wave be about 83.3% strength (putting it about 25% more than it is now). (The base AI strength increase may need to be more severe)
Then we can do the 2/3 reduction in AI scaling in return for this (if the base AI strength is buffed more extremely, then this will need to go down a bit more).
As the low AIP has been made harder, we don't need as much if any knowledge reduction per planet. Maybe knock it down to 2500 knowledge a planet (if the reduction in AIP growth rate is made more severe than 2/3, then perhaps 2000 would be acceptable)? That way, the human can actually grow in strength faster for more stages of the game (as the human reward per planet has not been nerfed as much), until finally you start to plateau near the limits of what knowledge can get you, and the AI starts overtaking you again.
Yes, this does make the early game harder (a little bit for mid to high AIP strats, quite a bit so for low AIP strats), but the late game easier. IMHO, this is a good thing, as right now, most late games devolve into "grind fests", and most early games are just too "boring" as the AI isn't doing much (which is the design intention, but right now, it is taken a bit too far IMO). Hopefully, the new non-lazy AI option should keep the homeworld from being a pushover. (Speaking of which, that AIP for the strategic reserves may need to come up some if something like this is done)
The exact numbers need tweaking, as I am sure the numbers I proposed will lead to a too early mid to late game without a proper increase in difficulty for the low AIP strat early games.
EDIT: Also, I do think base knowledge could stand to go down a bit, but not a huge amount.