Don't rip out that kale until you've tried its "broccoli"; I can't get enough of it.
What sort of arugula do you grow? Although I enjoy the salad type, sylvatica is a perennial on my farm and useful in measured doses; it gets a tad hot and pungent in hot weather, so it needs to be shredded or ground into things to be less assertive; the bees love it to death.
I think that's the deal with many brassicas/mustards; the budding stems aren't commercially valuable, so the plants get destroyed before they produce them, but they are perhaps the best thing the plant produces.
Granted, I don't know how this relates to chard, eating-wise; just let some plants go to seed and spread it all over; what's to lose?
I'll let the kale grow, it's pretty good in small amounts and it is a pretty plant, it is mostly Red Russian. Even though it isn't my favorite thing any food that just grows on its own is OK with me. I don't know what kind the arugula is but probably what ever is most common, the woman got the seeds and I just threw it in when I planted this fall. I don't know how it got dispersed but the kale is all over the place. The ones over by the shed are understandable cause I dried it down in there but there is also a plant out by the mailbox and some in the woman's flower garden.
Hope the same thing happens with the chard. I may just leave the old plants and mulch if it gets colder and plant more from seed in the cold frame.
Nothing ruins a neighborhood like paved roads and water lines.