Firstly because most of the water counted in raising kg of meat is rain, secondly because they eat unedible food for humans or, at least and as far as I am concerned, I can't digest grass and I'm pretty much ineffective to deal with cellulose.
Honestly I think it would still be better to skip the animals, even though they eat inedible food.
Not if you're talking about grazing and just straight up grass fields, but in any case where we plant food specifically for them.
Obviously if the food wouldn't be given to the animals, we'd also plant other stuff there to feed to humans.
And because the food goes directly to humans in that case, we would need much less fields to provide for everybody. The food-to-meat ratio is really had after all.
So in the end there would be much more space for just nature to do it's thing.
Some spaces are unsuitable for farming, which are typically whhat pastures are. Also, meat provides nutrients of better quality and easier to digest than plants, making the food-to-meat ration not so easy to speak about, so they still have a high value.
Where I agree though is in reducing (drastically) the amount of meat consumed and hence the animals we "raise" which use a lott of good soils or simply contribute to deforestation. Unfortunately, nowadays, I don't think that any of this is reachable because vegan/vegetarians ((the noisy part of this group) often blame people who eat meat for eating meat in a dogmatic and, hence, an innefective way instead of firstly focusing on reducing waste, which is shameful and would already be a great step forward for everybody, or by simply promoting quality over quantity and thus reducing meat consumption, but also by, often, falling for greenwashing and "green-capitalism", buying crap from the other side of the planet that is sometimes more detrimental than eating meat for ecosystems and climate
As for "nature to do its thing", that's a kind of misconception. Nowaday, such places barely exist anywhere, even in the areas people believe to be "natural". Most of the areas are highly managed and I believe your country is an extreme example of this.