Diplomacy, limited wars, etc...

[Suicide Junkie]

We could use a global badboy penalty for genocide.

In the meantime, I advocate setting:
Number Of Ground Combat Turns := 2
and
Planet Value Percent Loss After Owner Death := 40

With 2 GC turns per month, your ground pounders will be slogging around, slugging it out for years before taking a homeworld. Plenty of time to clear the skies and add reinforcements from both sides, for Troop-Vs-Troop action!
Emotionless races will be able to build defense troops the whole time, so they might actually be worth the 3000 points!

With a 40% loss (or even higher if you like), a nuke-em-to-glass policy will leave you with a barren, desolate starsystem even if you win.
Value-Improved Homesystems can be very valuable indeed!