"I’m talking more about architecting code instead of naively writing them."

Yeah, we are talking about code designing.

And I got my head filled with all the design patterns back then in university, but my first bigger real world projects were somehow horribly overengineered and still unflexible. And I don't think it was just lack of experience.

Nowdays I prefer a very, very simple and clear approach.

No dark empty space I want to design around.

No clever hidden layers, that prevent the introduction of a pragmatic new API.

I guess I get what you probably mean and it ain't that, but to me it has too much of the vibe of the time when I was amazed at myself for coming up with a seemingly super clever (complex) design, that sounded great in theory.

Yes simplicity is always important, but it does not equate easiness. The axe of simple to complex is independent of the axe of easy to hard. It may be easy to apply patterns blindly to your codebass and make it complex. Just how it is easy to write naive and simple code that then becomes difficult to work with.

The mark of a good programmer is to balance all of these so that it’s easy to work with the codebase on an ongoing basis. And more often than not it’s similar to the sketching process. At each stage, you get enough feedback to judge the right direction for the next iteration. You do not start with all the details, nor with careless doodling. But one aspect that is often overlooked with artists is how often they practice to get that judgement capability.