Why should anyone learn to write in cursive? A bigger question is why shouldn't everyone learn to write in cursive? Well, many people are assembled into rampaging mobs roaming the streets savagely copy-editing those who use the wrong word from the their/they're/there set. You could try teaching them, but they'll detect how you've never been sure about the difference between ``discrete'' and ``discreet'' and now that you think about it suspect they're the same word just being difficult. If the mob gets there, and I'm in it, I'll try getting you out of trouble by admitting that the more I see people writing ``coruscating'' the less I believe it's an actual word. I want to be friendly even in a furious copy-editing mob.
The naive view is that cursive is an elaborate method to turn handwriting into gibberish scrawling. This is unfair to cursive and not charitable to views either, and gibberish scrawling has its objections too, mostly based on not remembering how to make the ``G''. What cursive is really great at is turning a gibberish scrawling into letters. Compare it to how turning line noise into HTML works, or crumpling up wrapping paper into telegraphic Morse code, or dropping suitcases down steps and see how few letters that produces except from attorneys representing the suitcase-dropped-upon. Cursive is a time-saver, in comparison.
To build the habit of writing cursive set pen (or pencil) to paper (or papercil) writing tip down (or downcil) --- that last is important --- and pull it at a uniform pressure and speed from left to right. Wiggle the pen (or paper) up or down (or down or up) now and then (or then and now) and sometimes briefly lift the pen. When you've reached the end of the line, congratulations: you've written the word ``fiduciary'' over and over. Now add some dots to indicate where the letters ``i'' go, which may be done ... oh ... looks like somewhere near the start and somewhere near the middle of the word.
Writing ``fiduciary'' over and over may not seem too exciting, but just by doing this you've got the essentials of writing a stock offering. Carry this on for fifty pages or so and you can bring it to the London money markets in about 1821 and really clean up. Unfortunately now that it's so easy to get text printed up you have to adapt your technique, and print out many more pages before you'll get any investors.
If in addition to putting dots in you add some slashes against the taller vertical strokes then you've also written ``computational'' or ``trattoria''. Be careful that you don't add too many crossing slashes or you're in danger of starting to write in Icelandic with those freak things like the ``o with a plus sign growing out of it'' that they can't actually mean to be letters. You get more words, such as ``going'' or ``amanuensis'', by varying the length or the dot and cross count. You get fewer words by not varying them, and you get no words at all by leaving the pen and papercil out of reach. This is the ``is the computer turned on?'' of diagnosing cursive problems.
Today cursive's best application is the game show based on contestants attempting to read the postcards my mother sends from her trips. The core rules are obvious enough, contestants getting up to $1000 for each card they're able to decipher, with $100 knocked off for every time the contestant gives up and asks for help through a clue, such as by learning that this particular postcard comes from a trip to Portland, Oregon and therefore there's a chance it actually reads ``giant illuminated bread loaf''. To date the all-time best contestant walked away having paid the producers $700 so as to finally establish that this card was greetings from most likely Bratislava but possibly Chile. My mother's never been to Oregon. We're a bit concerned.
As no one remembers how to make a cursive ``G'', instead write in that little extra-loopy S-thing from the start of a sheet of music and move briskly on to the next symbol.
Trivia: A 1713 bill to dissolve the Union between England and Scotland failed by four votes. Source: How The Scots Invented The Modern world, Arthur Herman.
Currently Reading: From Eternity To Here: The Quest For The Ultimate Theory Of Time, Sean Carroll.