These were luxuries only our nicest tractors had growing up ~20 years ago. I imagine the market for an Open Source Tractor can similarly make do without.
Similarly flatlander recreational/club bicyclists don't have anything nice to say about farmers spraying anhydrous ammonia on a windy day. Luckily didn't happen very often, and never up close (>400 yards), but that's still enough to really get your attention.
Having occasionally used a (cabin-less) tractor without power steering for years, I'd pick that over a cabin for instance.
Dust and pesticides can be worked around with masks, goggles or scarves when occasionally found around. A straw hat for sunlight. In any case, this is a base building block, people are free to design add-ons for it depending on their needs :)
A box doesn't fix everything. You still have to get air into it from somewhere and it's all gonna come from outside. But sitting in a dust cloud is a little different situation than getting some dust through a vent. Especially if you're sweating like a pig the whole time.