I was taught cursive using the Palmer method in elementary school. It is one of the reasons that my teacher took a young, confused, left handed boy and forced him into a right handed mold. My hand eye coordination suffered, my penmanship was awful, and I even developed a stutter (which I later found out often goes hand in hand with forcing children to use their non-dominant hand for writing).
It wasn't until my mother found out that I was being forced to use my right hand and made a huge scene at the school that the official policy was changed. This helped out others who came after me, but for me the damage was already done. I am now ambidextrous, with a slight tendency to use my left hand for fine motor skill type things (other than writing, which I still tend to do with my right hand). Ambidexterity may seem like a good ability, but I often find myself getting confused as to which hand to use, constantly switching back and forth between the two (I've been told that it is odd to watch me eat). I tell people that I am equally poor at using either hand...except where pool is concerned. I can shoot pool extremely well with either my left or right hand, which means no behind the back shots for me (but plenty of surprised and annoyed looks from my opponents). BUT, being good at pool is hardly a fair trade for the difficulties that being forced to use my right hand have caused.
The Palmer method was the source for my school's policy, and it changed my life irrevocably. I often wonder how my writing and drawing would have turned out if I had been taught to use my left hand in my formative years. A system for teaching and for learning is always helpful, but rigidly enforcing mechanics that may not work for everyone causes far more harm than good.