Recently PETA came out with a campaign against woollen clothing. A couple of famous people got posed under slogans which said, basically, that they'd rather go naked than wear wool.
To which I'd like to say: dear PETA, there are many problems in the modern clothing industry, but wool is not at the top of those.
If you find cruelty during shearing a problem, please advocate for better treatment of sheep, and not against wool.
What would you, rather, see people wear instead? Synthetic fibres such as polyester which are petrochemicals and pollute oceans with microfibres? Cotton which is water-intensive to grow and gets sprayed with a variety of toxins?
PETA, you already argue against wearing of silk, and leather. If you now also argue against wool, what clothing, exactly, is there left? Linen?
Wool has excellent thermal properties. It is biodegradable. Durable. Many breeds of sheep don't even self-shed wool any more, so if such sheep don't get shorn they grow into unsustainable mountains of wool and eventually die, slowly, because they aren't able to see, or eat, from inside their coats.
Many sheep farmers are responsible, ethical people who care about the animals and are interested in their well-being. But just like with any other human-involved activity, there are some some who don't.
Advocate against those. Set standards and frameworks for ensuring quality in animal rights.
But do not advocate against wool.
Because otherwise you're insane.