Restrictive development plan - is buying land worth it?

Are you sure about that? I read it simplified like this:

2.1 Residential buildings have a floor area ratio of 0.1, but a maximum footprint of 110 sqm (i.e. for plots larger than 1,100 sqm, the footprint may only be 110 sqm, even though the floor area ratio would allow more, e.g. for a 1,500 sqm plot floor area ratio 0.1 = 150 sqm). The footprint of the house is the footprint I.

I understand it to mean that the house is basically allowed 0.1 of the plot area, but only up to 1,100 sqm. Above that, the absolute limit of 110 sqm footprint applies.
However, if the plot is larger than 1,100 sqm, the floor area ratio 2 (i.e. ancillary facilities) is allowed to exceed the floor area ratio by exactly this factor.
That means that for a 1,500 sqm plot, in my understanding you may still build 40 sqm with ancillary facilities.
If you cover everything completely with gravel, that probably doesn’t count, but that will not be the solution either.
I suspect that only small weekend houses are supposed to be built there, and no 200 sqm residential houses for permanent use.

But which regulation exactly do you think violates the land use ordinance?

Okay, I switched perspectives and read the provisions benevolently from the formulator’s point of view probably 100 times and found interpretations for the explanations so that no gross error exists. Two points of criticism remain: - In 2.2 terraces do not belong in the list for Floor Plan II. However, I also found an excuse for this: only freestanding terraces are meant, i.e. those that have a significant distance to the residential building. - "the feasible building floor area depending on the permissible floor area ratio" is not to be equated with Floor Area I, as the bracket wants to suggest. Since your plot is a bad example because it is exactly 1100m² in size, I choose a plot of 900m² as an example. Regarding 2.1: A residential building may have a maximum floor area of 110m² regardless of the plot size. A residential building on the example plot may have a maximum floor area of 900m²*0.1=90m². Since single-story is required and only full stories count, "the feasible building floor area depending on the permissible floor area ratio" amounts to 90m². Regarding 2.2: The floor area for driveways, ... (Floor Area II) may be 180m² in size, or even more in exceptional cases. So on "my" example plot fits a 9m*10m=90m² house with a 4m*5m=20m² adjoining terrace, a 3m*30m=90m² long driveway, a 6m*9m=54m² double garage, a 4m*8m=32m² pool and a 2m*2m=4m² tool shed. Floor Plan I: House + terrace = 90m² + 20m² = 110m² => permissible Floor Plan II: 90m² + 54m² + 32m² + 4m² = 180m² => permissible

2.1 implies single-story construction (floor area ratio 0.1) If they were weekend properties back then, the development plan makes sense. I think so. And I also find it okay. Actually, I always had the question on my lips while reading why you insist so much on 200sqm. It may be that you need it (then it's not your property), but maybe you also don't have a realistic view of room sizes. But well: even with 160sqm you should give up the property. Nature lovers and hermits will have their true joy on the properties.

2.1 implies the single-story construction (floor area ratio 0.1)

In 4 it even states explicitly:

And I also find it okay.

I don’t think so. The formulations are quite peculiar. I wouldn’t be surprised if the justification for the development plan disproves my interpretations. While searching for this, I came across a newspaper article stating that a norm control procedure is pending. So there are at least indications of possible illegality. Obviously, this has been disputed for over 10 years, so the development plan should speak clearly by now. A development plan is supposed to show citizens the possibilities of construction and not cause confusion with Kafkaesque formulations.

Escroda, but you and I and Meyer and Müller can just go to the local town hall and ask, what do you want, I only half understand that, tell me.....Man, only the speaker can be helped. Of course, much clearer usual sentences would be nicer. But 10% floor area, 1 floor, 110 max. is already quite precise.

only the speaker can be helped

Yes, but statutes are written, after all. And if it's only about the property purchase at first, a local consultation appointment is already a big ask.

But 10% floor area, 1 floor, 110 max. is already quite precise.

Relative floor area, absolute ground area, percentage exceedance possibility of a ground area, which has to be derived from a relatively limited floor area, the undefined terraces, the bracketed additions (ground area I / II), is anything but precise. As if the ground area ratio/floor area ratio calculation were not complicated enough already, here one deviates from the requirements of the land use ordinance in an hardly comprehensible manner. Therefore, initially my suspicion - which has not yet been completely dispelled - that these formulations are not compliant with the land use ordinance. It's a pity that the justification is not available online; I would find that really interesting.