Stu, I think you will find that EU subsidies put quite severe constraints on what farmers can and cannot do with their land.Many of the practises you accuse farmers of are illegal in any EU juristriction, and increasingly non standard agricultural practises are becoming subject to planning permission. Bats are a protected species as are many other species of wildlife. Overgrazed uplands are a matter of opinion. In Ireland the opposite has become the case on many commonages. As the vegetation ages it's nutritional value and palatability diminishes and thus diminishes the value of the grazing.In reality the vegetational types on the uplands are a result of anthropogenic influences rather than a natural plant progression. I do not agree with many farming practisies especially arable, but unfortunately we have developed a system requiring high mechanisation with high inputs for high outputs. Thus is the way to cheap food. It is a rare person can act on the moral high ground and accept the consequent massacre of income. To change the present system will take far far more than just vilifying farmers.

On a happier note I refer you to the Irish GLAS scheme
There are many positives as well.
https://www.agriculture.gov.ie/farmerschemespayments/glas/

and the Hen Harrier habitat mapping:
https://www.npws.ie/news/hen-harrier-spa-habitat-map-viewer-published