Because you were citing historical documents as a need to know English so I was pointing out that historical documents almost never have or will need knowledge of cursive, just like archaic English. If your argument is that you'll run into and need cursive in your daily life I see no situations where that'll happen past someone giving you a gift and writing it in cursive which is specific and unlikely. Also when I mean archaic English I don't mean figuring out thou means you, I mean the kind that in indecipherable to most people but available translated. For example Beowulf. Not Shakespeare. If cursive is similar to that then no one would be able to read it. And I can't say that I would feel any better about learning old English and being able to read the original copy of Beowulf rather than needing a translated version with the same information without going through the effort of learning Old English. I don't see cursive as different. The content is what matters to me, not whether I saw the old old version or copy of the old version with the same exact information. I think most people won't care about or need to see full texts of historical documents ever, let alone original copies of any historical document ever. But if they need to, they can probably find and understand these documents just find without squinting at faded old papers trying to decipher the letters. Cursive is rarely going to be useful for any understanding of historical documents for the layperson, if ever.
Many things are good for the brain, can help with motor skills, comprehension, you name it. Some will probably even end up having better effects that sitting at a desk writing. You definitely can't think that writing cursive is a make or break for any of those areas. Why not do something more productive that can help with similar or different areas? A few cursive classes won't hurt (aside from kids getting annoyed and unhappy, which is often what I feel happens in the end) but in the long run they realistically will help in almost no way too. Why teach something that is basically useless to almost everyone when you can wait and teach is just as well to anyone who does need it later on specifically?