You don’t have to write the same thing to everyone here. Everyone reads it as if in a conversation.
Because your argument/feeling is unfounded. It does rain very often in Germany, but mostly at night. You are not the only one who thinks it rains EVERY time he comes home and 4 meters along the house wall leave you soaking wet. That’s not the case!
And to misuse an office or another room that is not a hallway as a hallway reduces the personal living value of the space, since it then becomes just as maintenance-intensive as a house hallway and has to be equipped with door mats and boot jacks. You also don’t go to the kitchen to pee.
You are not moving in now, you are not building for one year, but hopefully for at least two generations. And even if it’s only 20 years: life will change, in purchases, values, and especially in food production and storage.
Door widths are among other things standard. How do you want to get your heating system into your place?
If the data here is correct with 40 degrees roof pitch, then your 2-meter mark is simply wrong! You have a max knee wall height of 130 cm... with an inside recessed dimension of about 80 cm you have your 2 meters. And at that height, I certainly see no shower fitting. Or do you want to say now that your windows have the same height at top and bottom or that the two windows in the upper floor are 3 meters high?
I don’t think much about what is not going to be built anyway. I already mentioned: The budget does not allow for a basement. Therefore, a new plan has to be made.