I don't like petitions. They are not really representative of what people want.
Money is the most motivating factor for a company to change, so I put my money where my mouth is and won't buy the DLC. If enough people feel the same way, they also won't buy the DLC and then Frontier will have motivation to change.
If most people are happy and they do buy the DLC, then why would Frontier change something that is working for them? Money speaks louder.
I understand what you are saying, and that is a strong point you are making. You are entitled of course to your own opinion. But the petition is just for more animals to be included, it seems to be the general consensus in most forums where this game is being talked about. At the same time I want to support Frontier and the team behind Planet Zoo, they seem like wonderful people. There is also the negative factors that are associated with not purchasing the DLCs, it could be misinterpreted as lack of demand or interest in the game. The company needs to be made aware of what is going on, so they know how to correct it in a way that the majority are satisfied.