I can only speak for neos, because that is what I have the most experience with.
The only thing needed for neos, IMO, is a container, sponge filter, substrate and a plant to help with water quality. Boom. Done.
We like to try to make awesome environments because 1) WE like to feel like we are doing something, and 2) we want to see how we can set up the best environment possible.
In addition, as a selective breeder, I like to try to get the best yield so I can further my projects faster. More babies = better chances of getting closer to my goal. (More culling too, but my fish don't mind. LOL)