I've noticed in my entire time doing the children's toys mission that the majority of consoles you get tend to be borderline useless. As shown by OP, the more useless consoles are created more often. I personally find that to be rather annoying, but it's how the game works... I mean after all, there is a reason that mk XII purple consoles are called VERY RARE lol...
I found these results interesting enough that I decided to dig into the reward structure of console fabrication. Since these were created under Heretic, I truly didn't know what to expect.
Here are my findings:
1) The quality of the reward outcome of the "Fabricate Prototype" assignment is guaranteed to match the quality of the success' display name. In other words, if your results say "Blue Quality" the console you receive cannot be anything other than Blue (Rare) quality, in all circumstances. No rare chance to upgrade to a better type, or anything like that.
2) Every console available from our random drop tables is represented. Despite the above sample showing zero Phaser Relays (e.g.), they are included in the drop table as a possible result.
3) All console rewards are equally weighted. This is the part I was unsure would be true, but it is - every item on the reward tables has an absolutely equal chance of being rewarded.
The only possible explanation I can offer at this point, is that it's just a matter of sample size. There are 42 different Mk XII consoles you can receive from this assignment (16 Eng, 10 Sci, 16 Tac) of each quality (Green, Blue, Purple) resulting in the total number of potential outcomes being 42*3=126. When you run a sample size of 300, with almost half that many possible outcomes, your odds are invariably going to be too small to create an big enough picture of the entirety.
Cryptic - Systems Design