I save time in the long run, and learn more on the way.

I find this hard to believe.

If I were to summarize your post, it would reduce to "I don't like these other things because I don't understand them."

Granted, there are modules with lousy interfaces -- some of them are in the core. Granted, there are modules that don't do their jobs very well -- some of them are in the core.

For all but the smallest jobs, though, I personally don't have time to research the laws of physics, come up with my own propulsion formula, and devise ceramic heat shields for my own spaceship. I've had far, far better success from learning to read code and documentation than by trying to write everything on my own.

I've finished planning... Now comes the implementation.

This is telling.

Perhaps the reason some of the modules seem too complicated is because you don't understand the problem space well enough. How can I say that? Because you don't have any code yet. I've never seen detailed plans for any significant project survive the first couple of weeks of code. Things change too much.

Of course, I'm not the world's best programmer. You could be a lot smarter than me and it could work out very well for you. In that case, just treat my post as a yellow caution flag waved from my experience. People prove me wrong all the time.