Complete all Sets!

Ok. This might be an old topic, I can't be bothered to open the forum search to look at 50+ related topic so if you think this is an old topic then don't reply.
And I don't expect Ankama to incorporate this in the game, this is for the purpose of discussing and suggesting an innovation/improvement.

So here goes:
Why don't some set include the pet that is obviously related to it?

Gobball Set add Gobtubby
Tofu Set add Tofrazzle
Chief Crocodyl Set add Crocodyl
Chief Bwork Set add Bworky
Godfather Set add Godfather Gobtubby

Additionally why are some part not considered as a set when they share the same name? example Crocobulio equipments?

I invite everyone to add any pet or equipment that should be considered as a SET part.