[henk brouwer]

I didn't care much for neutrals in SEIV since the other AI empires did not know what to do with them, which gave an advantage to the player.

In most SEV mods however, the AI has learned to deal with alien populations, so they too can take advantage of conquering weaker races. The main reason for making neutral races is however the simple fact that it would take me ages to complete shipsets for all these races :-), and even with neutral races switched off, it will give you some extra race portraits to choose from during game setup.