exactly, but imagine if you were competing in some sort of death tournament, where you rolled for what weapon you'll use. everyone has the same chance to get any given weapon, but then you have to watch a fight where someone is fighting a dude with an assault rifle with a ladle. it's not fair, even though they both had the same chance to get any given weapon.
the point is this system, isn't "fair", and by reducing rng and increasing the base minimum, you make it fairer, and don't have quite the same odds, now their both at least fighting with swords now, even if one is a bit longer.
But since assault rifles are in the equation, that means that even though everyone starts with swords, the fact that an assault rifle can still randomly appear in the hands if one of the combatants then that means that there is still a chance that the crowds going to be seeing an unbalanced matchup, once again creating the same situation as a ladle and an AR The same logic applies here.
No matter what the contestants (races) enter the arena (galaxy) with, as long as there is a chance one of those contestants can end up with a power advantage just due to rng, then there is never a truly *fair* start regardless of what the base weapon is.
Btw, your AR/Ladle analogy is the entire foundation behind the popularity of the whole Battle Royal themed books, movies, and games. You describe the sensation of never knowing what you are going to end up with as unfun or worse, boring to a spectating crowd or the participants themselves when it's the exact opposite.
I'd buy a ticket to see that potential AR/Ladle fight just because of the potential of seeing something amazing, and its no different with Stellaris. Others as well as myself who would prefer this be an option instead of a strict standard simply enjoy the excitement of never knowing what you or your fellow competitors are going to get, then the challenge of making the best with what you've got in the case it's not that great against tough odds or pushing that rare advantage to it's absolute limits. But I understand some don't enjoy the thrill and challenge of uncertainty, hense the need of an option at galaxy creation.