I've certainly cut back on my meat consumption, but still eat it, so veggies are definitely a thing that cast iron can do. My favorite thing about cast iron is that it can do everything. I can use the same pan to sear something, then finish it in the oven. One of my favorite recipes does just that (in a dutch oven) - roast chicken with vegetables. Sear some chicken breast on the stovetop, put a bunch of veggies in the dutch oven for a bit, put the chicken back on top, cover and put in the oven for an hour. Tender chicken and veggies. I have a similar recipe for chicken with garlic and shallots too. Not to mention the fact that I use the same skillet to cook anything on the stovetop and then turn around to bake some cornbread in it.
And actually, bacon fat isn't necessarily the best thing to use to season cast iron. It's not bad, but it can go rancid if you don't use your pans often enough. So if you use it, bacon's great. But in my limited experience restoring my great-grandma's cast iron pan from scratch, canola oil works just fine, and is faster and easier than cooking numerous batches of bacon. (If admittedly, less tasty to most.)
Any good vegetarian recipes to share? I've been meaning to try more, as not only can they be much healthier (i.e. often fewer calories) than some meat dishes, they're often cheaper! And with the way groceries have been lately, I can use some help keeping the bill down. (And just spend the extra on more bass gear...)