I suspect it's a shame that you didn't query it in the meeting because they'll now be able to fob you off that 'everybody else agrees it's a brilliant idea' whenever you say something to them about it. But I know it's not always easy to do!
I would definitely be talking to the teacher and the head - maybe raising the queries in writing or following up the meetings so there's something in writing raising your concerns and querying their methods. I'd also be double checking exactly how they are planning on going about doing this - raising the NSPCC example as we've seen on this thread that there are ways of doing this nicely and not. And finding out what they are doing about books falling apart, keeping old work to compare against, lack of evidence for OFSTED and so on. And most importantly are they doing against a set standard of what is good enough or on an individual child basis?
ds1 (11) has beautiful handwriting and always has - DS2(8) on the other hand has completely illegible handwriting (to me, his teacher managed to read it last year) that looks like a spider has crawled across the page. I blame his infant school - they jumped straight into teaching them to do joined up cursive writing without printing first in his year (unlike his brother's year!) and he has really struggled. He's not dyspraxic but is somewhat hypermobile so really struggles with pen control.
Luckily his last couple of teachers have been really lovely and have both said that he's a bright boy and that they'd much rather have a messy but interesting homework than a neat one that shows no thought or care. His teacher last year used to get him to do handwriting practice when the rest of the class were doing sums or spellings or whatever at the start of the day because he knew he could do them with no problems, so hoping that his teacher this year will do something similar with him.
He loves working hard and gets really upset when others in the class misbehave - so if he had a misery guts teacher who relished ripping pages out for bad presentation, he would have a horrid year.
Interestingly I know a ta at the junior school that lots of the infant school kids went to - she says that since the infant school changed its handwriting policy (to be fair to them, think it is a government initiative rather than one of their own) about 2/3 of the joiners have beautiful handwriting, the policy worked for them and that's grand. However, the other third really really struggle and have really bad writing - a much higher proportion than previously... So for those that are good at handwriting, the policy seems to have improved their handwriting further so you can see why somebody thought it would be good to roll out the scheme further... But for those that struggled before - now they're really struggling. And for such a basic but important skill, and for such a significant number within the cohort, it really is appalling that so many are being failed by the rigidity of having to stick to guidelines that are not working for them.