It replaces uncountable diversity of unique life with a cow. That's a huge loss that can't be recovered for millions of years - as we're quickly erasing entire species.

On other end should we also work towards increasing biodiversity in locations where it has already been decreased? Let's say destroy suburbs, promote growth there, move all people living to most optimal space usage. Let's say 2-4 people per 3 m^2 rooms. Shared bathrooms and so on? Would allow us to claim back lot of land and start reclaiming it for nature.

Not if you’re hungry.

There's plenty of food to feed everyone on this planet. The problem is not the production of food, but the distribution.

Destroying ecosystems and species rather than solving that problem seems a little .. well, short-sighted at best.

You solve the food problem one way. Your neighbors solve it a different way. Vines, still another way.

If your neighbor cuts down the forest to raise some cows, or a vine climbs up a tree and chokes it out to access more sunlight, where’s the right or wrong there?

Because as I already noted, there are two distinct problems: food production, and food distribution.

We already know how to produce enough food, new efforts to increase food production (other than coupled to some combination of local/global population change) are unnecessary (0). Therefore, destroying ecosystems and/or species to solve a a solved problem is at best less morally defensible.

The actions you've described are about food production, and thus I regard them as less morally defensible than things one might do to solve the problem of food distribution.

[0] I would note that we might still seek to change where food is produced, and what precise foods are produced, but I see that as a different question, mostly.

we’ll all be hungry when we turn the entire planet into a desert

We have much better ways to make food than cows. If you're hungry you don't go raise cows. You go farming. Much less space needed for the same result, it's much quicker and with way less risk.

Yet, people are still raising them for food. The species under question doesn’t matter. Farming is also destroying diversity so that people can eat.

There is nothing wrong here. It is the way of nature. As you read this, bacteria, viruses, and fungi are trying to do the same thing to you. The earth is green because the plants are also trying to colonize everything.

So what? It's scale that matters. Humans are absolutely incomparable to the natural effects you describe. We're brutal. One human is capable of transforming absolutely humungous areas of land in short amount of time. And there are billions of us.