Wish FA had multicore support and 64bit, but you know it will never happen. Planetary Annihilation has a solid foundation for many changes though.
And as I said, the planets in the screenshot have a 400 radius size with the size going up to 1500 for normal planets, 3 times larger planets.
And don't forget that double radius means 4 times more surface area due to it being a sphere! O=4*pi*2² This means you get 8 times more space compared to the screenshots above to play on on the largest planets which is even larger than most common FA maps. And there are already mods which scale units down to 50% if this still is not large enough for you.
One unit (even titans) never take more than a mere % of the map on large planets. And they are harder to build than in Forged Alliance and even there a large experimental takes 1% of the map spacewise.
Most maps have more than one planet. I prefer playing with a large planet (max radius) and a small planet like the ones in the screenshot as a possibility for sidebases and sneaky orbital strategies. (all this can be countered - the game is pretty balanced unit wise. Every unit has a purpose and I normally build at least 70% of the unit types depending on the planet type in a normal one hour long match) For example there are some slightly more expensive tanks for their damage and health which can hover over lava. (only unit which is not air and can do that) And one ship type which is slightly weaker than the others but can hover over land. (which costs energy while it doesn't eat energy to move in water) And a real orbital layer opens up many strategic possibilities. I think it is a great game now that the titans expansion got us many more options and changed the balance around a bit. But it could be much more than "just" being great. It could be amazing. And mods would help greatly.
Sure, adding too many units would destroy the great balance right now, but adding just a few in spots which are still missing (like a titan radar and adding some experimental stats to the titans for example shutting down for a few seconds after attacking if the HP is below 30%)