"AHMAGAHD FINDING NEMO DOESN'T NEED A SEQUEL BLARGH!"
Let's clear up a few things:
1. Plenty of people loved Finding Nemo (My son is almost 3, and he knows all the characters by name)
2. Plenty of people payed to see Finding Nemo
3. Finding Nemo was made 10 years ago. (Holy fuck I feel old) So there are people who were born when this first came out that are able to enjoy this movie now. They are the target audience.
4. If you have the critical thinking skills to consider that it doesn't need a sequel, you are NOT the target audience.
5. Sequels aren't made for the hell of it. They are made with the expectation of it selling as well if not better than the previous movie. Bottom line: They make sequels because you will pay to see them.
Yes, I know, folks have their own opinion, but consider the target audience, and consider that you may not fit that target audience.