The last two posters have pretty much hit the nail on the head for exclusion of a good deal of the original KJV material: cost.
Paper was expensive in a pre-industrial age, and reducing the number of pages (unlike today) greatly reduced the cost of printing. Marginal notes, obvously, take up a lot of space and require more time to set the type.
I'm sure the publishers pocketed some of the difference, but leaving out the extra material also meant they could produce cheaper editions, making Bibles more affordable and widespread.
An example is the Aitken Bible, the first English Bible printed in America. The 1782 edition is strictly bare-bones: Chapter numbers (but no headings) and verses, printed on wood pulp paper. And, of course, the Apocrypha was omitted.
Eliminating the extra material also made the Bible smaller and easier to carry.
In addition, some of the material was redundant; with the publication of the 1662 Prayer Book, it was no longer necessary to keep the appointed Scripture readings (or how to find the date of Easter) in the Bible itself.
The Epistle Dedicatory lost favor during the Commonwealth and Restoration and, on this side of the Pond, after the American Revolution. (This change was not instantaneous; Isaiah Thomas' 1791 edition, printed in Massachusetts, proudly proclaimed that the translation was By special Command of King James I, of England; whereas Isaac Collins' 1791 Bible published in New Jersey not only eliminated the Epistle Dedicatory and reference to James on the title page but also noted that the dedication was "wholly unnecessary" and "perhaps to be continued in an American edition" and that he had been advised by some "judicious friends" to omit it.)
As to the Apocrypha ... I have been unable to determine the first KJV to omit the disputed books, although it would appear to be circa 1630 (perhaps a bit later). It had been illegal to publish an English Bible without an Apocrypha since 1615, and it seems the government had more or less enough power to enforce that decree during James' reign, but his successors had neither the power nor the inclination to do so.
The Puritans and Presbyterians, for the most part, had no great love for the Apocrypha, and as their numbers and political strength grew in the 1640s, there was a greater market for editions without the Apocrypha and, probably, less stricture about their publication.
After the Restoration, a primary market for the Bibles was among the Dissenters, who preferred their Bibles without the extra books. Thus the KJV was published in both editions, with the ratio gradually favoring volumes that excluded the Apocrypha.
The American experience with the Apocrypha was mixed; the Thomas Bible contained the Apocrypha; the Collins Bible (Oxford edition, with notes) did not. The Philadelphia Baptist Association, in endorsing the Collins Bible ask that the committee formed to oversee the work "be ordered to use their influence to prevent the Apocrypha, or any Notes of any kind being printed and included in said edition, as having a dangerous tendency to corrupt the simplicity and truth of sacred Scritpures, by being thus intimately associated with them; and, particularly, as being incompatible with the union of people of different religious sentiments in promoting the work."
The death knell for mass-market volumes with the Apocrypha came in 1826 when the British and Foreign Bible Society decided it would no longer distribute Bibles that contained the Apocrypha; the American Bible Society quickly followed suit, ensuring that the Apocrypha would be excluded from the vast majority of printings.