Continuing on through the first paragraph of the original preface to the Book of Common Prayer, we read (emphasis mine):
"There was never any thing by the wit of man so well devised, or so sure established, which in continuance of time hath not been corrupted: as, among other things, it may plainly appear by the common prayers in the Church, commonly called Divine Service: the first original and ground whereof, if a man would search out by the ancient fathers, he shall find, that the same was not ordained, but of a good purpose, and for a great advancement of godliness: For they so ordered the matter, that all the whole Bible (or the greatest part thereof) should be read over once in the year, intending thereby, that the Clergy, and especially such as were Ministers of the congregation, should (by often reading, and meditation of God's word) be stirred up to godliness themselves, and be more able to exhort others by wholesome doctrine, and to confute them that were adversaries to the truth. And further, that the people (by daily hearing of holy Scripture read in the Church) should continually profit more and more in the knowledge of God, and be the more inflamed with
the love of his true religion."
-1st Paragraph of the Preface to the first Book of Common Prayer, AD 1549
This is the very crux of what Cranmer had in mind with liturgical reform. He was not reforming the liturgy for the mere sake of expunging all evil Catholic influences that had corrupted things over time, though historical corruption was an issue for him. His primary goal was to get back to having clergy know what the Bible actually said. This was also a major theme of the Reformers: getting back to the Word of God.
Protestants were already by this period advocating Sola Scriptura, or "by Scripture Alone." This was often the underpinning of their rush to throw off Roman claims of Holy Tradition and Obedience to the Holy See. If they could but prove that the Catholic church was wrong on what the Bible said, then the doctrine was basically self-justifying in their own minds.
As I have stated before, Cranmer is a hard read in terms of what he actually personally thought on the matters of Protestant theology. Particularly early on in his reform (in this case 1549), how much he had embraced this notion of Sola Scriptura is somewhat sketchy. He had certainly pushed (carefully and politely) Henry VIII to have an English bible accessible to all people placed in every church in the realm. Henry VIII, being at least in his younger days a staunch defender of the Catholic faith, was very moody on this issue, as he tended to err on the side of theological conservatism. Several times in Henry VIII's reign, he vacillated back and forth on allowing and then disallowing public access to the Bible in churches. He finally allowed it permanently, but he was most uncomfortable with the idea for most of his reign.
Cranmer, however, believed the Bible to be central to clerical understanding, debate, and spiritual growth, which is evident in the later half of the first sentence in the original Preface to the 1549 Book of Common Prayer. Exactly how much sway Holy Tradition, traditional (read: Catholic) understandings, and orthodox interpretations of the Scriptures had in Cranmer's mind, particularly at this point in his career, is unclear. What is clear is that Cranmer believed that reading the Bible and having a thorough knowledge, particularly by clergy, of it was vital to Christianity.
In fact, Cranmer largely came up with the first version of what we might call today a "Read through the Entire Bible" Lectionary. His entire concept of Morning and Evening Prayer every day was premised on reading through the Bible entirely. He combined many elements of the monastic hours (the daily offices said by professional monks who prayed several times a day). Cranmer largely combined the first 3 monastic offices into Morning Prayer, and the final 3 monastic offices into Evening Prayer. This was to make prayer accessible to everyone, but primarily to make sure that if you did morning and evening prayer every day, you would read through the entire bible within a year or two. If memory serves, his first draft of the daily office lectionary time table read through the Bible in one year, and subsequent editions whittled it down to two years.
All this was so that clergy and ministers by knowing the bible could "be stirred up to godliness themselves, and be more able to exhort others by wholesome doctrine, and to confute them that were adversaries to the truth." It was the law in England, and still is to this day though it is not enforced, that Anglican ministers must say Morning and Evening Prayer every day.
Frankly, I cannot argue with that. I often think if our clergy had a better understanding of the Bible, we would not be in the mess we are today over various doctrines that plague the church that are clearly contrary to the plain meaning of Scripture.