I half agree with you, Tyler.
Here in Scotland, vast swathes of privately-owned land are given over to three things: sheep, grouse moor and deer, all of which are massively overpopulated, in the interests of rich landowners, at the expense of massive public subsidy, as well as increasing soil compaction (in the case especially of sheep) and discouraging reforestation. In England the problem is skewed towards sheep. Another consequence of this is flooding, since rainfall can't soak into the soil, which is only going to get worse with climate disruption, because of the increased incidence of extremely heavy rain.
There is a push here towards both reforestation and rewilding (and the two camps are in the process of more or less formal merging), but it's coming up against those vested interests. Even the beaver reintroduction has run into problems because the landowners object to them eating fish. Yes, we really are facing that kind of willful stupidity.
As you correctly point out, one of the "justifications" for grazing is that these habitats would quickly revert to forest. Well, yeah, fine. That goes for my backyard as much as it does yours. Being able to eat meat because they want to "preserve" these impoverished habitats in order to keep eating meat turns into a circular argument.
Then there is the question of supplementary feeding. Around 70% of the world's grain and 90% of the world's soya goes to feed livestock. It's true most of this is going to intensive feedlot-type arrangements, but even here grass-fed cattle still get supplementary feed. I imagine the same is true where you are. How many Permies feed their chickens purely off scratch and kitchen scraps?
Let's reforest 50-80% of the grain and soya land and cut right back on the meat production. Let's convert those grasslands to forest - some of it semi-natural, some of it food forest, and cut out the carbon dioxide and methane from the livestock in the process. Win-win-win.
Where you need to be cautious is the question of ponds. I have not done a proper literature survey, but here is one from your neck of the woods.
http://link.springer.com/article/10.1007%2Fs10661-013-3474-y#/page-1
In a study comparing forests with conventional crop land with ponds, the conventional crop land was better at storing carbon than the ponds, but the forest was better than both. I agree there is a place for ponds in forests, just as I think there is a place for open glades, but they should not be overstated as carbon reservoirs.