I think anyone who has created a custom race knows firsthand that the robot that talks to you when you finish researching is has a distracting, jittery animation that makes it hard to look at. Each of the default factions has a unique animation on this screen, with the Terrans having an actual scientist, but this animation doesn't come with the tech tree when making a custom race.
Today, I'm looking at each of the tech trees to get an idea of how to build my own tech tree, and the easiest way to do this is to start a new game with a default faction. When I see the Altarian tech tree, I noticed that it has the exact same robot as the Custom Race tech tree, except it's animated beautifully! It's smooth, reflective, expressive, and even goes through all the same animation cycles, except way better. It almost makes the Custom Race robot look like a placeholder.
Why don't the Custom Races use this robot too? It seems like it would be trivial to change this. I must stress that despite the significant animation upgrade, it is literally the exact same robot.