But what if what you invent is deeply simple, after you've worked out everything and spent years simplifying? What if it is 10 lines of code but it solves a big industry-wise prod or exploitation problem? The concept might be simple but might necessitate years of effort to find and validate?

After reading constant praise about simplicity here on HN it always sound like cognitive dissonance to then read when patents are mentioned that something 'simple' should not be protected.