@Klaus *****
The Non-OA visa is a 12 month visa that you would need to apply for in your home country and it requires police checks, medical certificate and insurance. The Non-O visa is a 90 day visa that can be applied for in different places and requires none of those things. Both can be extended by 12 months inside Thailand if you wish to.
It's not that Thailand doesn't want you, it's that it wants you to be on an appropriate visa. You simply can't spend prolonged periods of time inside Thailand on short term tourism stamps, that's not what they are designed for.