Why People make the code so complicated

Generally, to make it less complicated than the alternative!

We don't normally make things more complex than they have to be without good reason. Sometimes, that reason is "we didn't know any better", but generally speaking we make things more complex than they seem to need on the surface because they aren't as simple as they seem, or we want to allow for future changes. We also do it because it is a lot easier to work on as a team, rather than as a single individual.

You can do anything without classes, without interfaces, you can even do it in assembler or machine code, but then the complexity of the code actually increases, because the interconnections between things increases as well. Adding classes and interfaces organises code better, so it is more reliable and understandable than a monolithic piece of code.

And anyway: it depends on what the end product is. Some things look really, really simple in principle, but in practice are hideously complicated. Take a rocket: fuel in, light, lift off! Simple, right? Now have a look at a Saturn V launcher and tell me that is simple! :laugh: And trust me, NASA didn't add anything they didn't have to because the launch costs go up exponentially with mass...