Why would Dr. Seuss write something about the environment and why have it in less comprehensive audience? As for my understanding during Dr. Seuss time it is very hard to go up against with big names and big companies. People standing up to their believes are being suppressed by powerful tyrants. They would not listen to any thoughts about the environment and the effects of what they are doing. Perhaps that's one of the reason why Dr. Seuss made it into a children's book. Also I think he got the idea that if you want to change the world start with the kids and children's books are one of the most powerful influencer. Kids read books whether it is in school or at home.
Not really sure if he had read Jose Rizal's writings but the idea of teaching the young ones the importance of the environment and letting them picture what will happen is somewhat similar to Jose Rizal's famous quote “the youth of today is the hope of tomorrow” (not exactly as it is but the thought is close enough).
The story of The Lorax does not only talks about the environment but it does show ideas of the economy as well and how filthy rich people takes advantage of different situation. In other words greediness comes in, moral issue is much more likely. Being opportunistic is not bad but grabbing the opportunity in the expense of others is not a good call of success.
Remember the story of a young girl who stands and talks about the environment in front of the representatives in the United Nations (not sure if it is a conference or a summit)conference? Yes, she made the whole world listen to what she have said and perhaps that was the start of the change. Just like the quote in Dr. Seuss The Lorax “unless someone like you cares a whole awful lot, nothing is going to get better. It's not.” It is indeed that unless there's one person that will make a small act, not only for the environment but also for the next generation to come, things will for sure change and it's for the better.