The move away from hyphens in favour of writing some previously hyphenated words either as one word or two (a minefield in itself) occurred in Scotland when I was in the fourth form. I can clearly remember Mrs Holloway our form mistress going through to-day becoming today on the blackboard. The year must have been the school-year (school year) of 1956-57.
I don't remember what else apart from to-day, form-mistress, sewing-teacher and the like lost their hyphens then. I do know it has got much worse since.
I still write co-op if I mean the chain of shops, as coop is what I would keep my hens in, if I had any.
Incidentally, when did it become incorrect to punctuate as I just did in the previous sentence?
I was taught that a subordinate clause was always separated from a principal clause by a comma. Now you are only supposed to separate the subordinate clause from the principal by means of a comma, if it precedes the principal clause and not if it follows it.
Sometimes I feel the changes in spelling and punctuation actually make it harder to write correctly.
Admittedly, which words should be hyphenated and which should not was always a peculiar discipline. Form-mistress with a hyphen or in two words schoolmistress in one word, like headmistress/ headmaster, and so on and so forth ad infinitum.
(Yes, I am still a strong believer in the so-called Oxford comma : comma before "and").
And I was taught to leave a space or half-space before colons and semi-colons, which rule no longer applies either, due mainly to the computer keyboard not having a half-space forward key like the typewriter did.