The critters was my idea to counter a problem that I see in the current game mechanics. Of course, I have not yet explained where I see the problem.
The problem is no-lights-armor, enemy night vision range and camo. With the recent night vision gui, playing in darkness has become viable, something you wouldn't have done before. With the no-lights-armor, you can now hide in the darkness, which is not possible in vanilla. Most early game enemies have night vision range of 9. This makes playing a night mission preferable to a day mission, especially with the 40 vision range during the day. Playing at night is basically the answer to the 40 vision range. Now add in guerillia gear with camouflage 5. When in darkness, enemies with night vision 9 now need to be 4 tiles away to see you. This is equivalent to haveing full smoke cover on every tile that is in darkness. It's even better than smoke, because you still have night vision 12. If you want to see further, just throw a flare. To kill the light, pick the flare back up or destroy it.
Remember playing vanilla night missions, back when you didn't know how to use flares properly? Thats what the computer is now up against. But he has not the faintest idea how to handle the situation.
Tl;dr: with guerilla outfit at night, night vision 9 enemies become a joke.
Why I wanted to have a chance of blood dogs on civilian missions was because these have night vision 16. With guerillia that gets reduced to 11, so still not that dangerous, but better than compleately harmless 4 vision range civilians. My civilian missions I play like this: put guerillia gear on everyone and a shotgun with rubber shells. Sit in the darkness in front of the enemy ship. Press end turn until every civilian has died fallen to reaction fired rubber rounds. No need to even move most of the time, just the occasional reload.
Adding more night vision capable enemies is a possible solution to that problem but not the only option. Camouflage for example could have an added minimum detection range variable, 9 for example. That way, guerilla gear would reduce the night vision of osiron security from 16 to 11 (which is really helpful), but leave night vision range 9 enemies untouched. Or someone can teach the AI how to uses flares...
Just to add, critters would still be cool even with the night vision problem resolved, because you have more stuff to shoot. With the possibility of blood dogs, I finally found a reason to carry a pirate assault cannon around. I like that gun, but there is a lack of viable targets, meaning targets where that gun is actually your best option.