The church is basically conservative, and keen to hold on to the "good old" rather than move to radical new ideas. I fully support this thinking overall. Generally, fads come and go. They often seem good at first glance, but time proves them wrong. Along with this, the church has held to using the good old KJV (King James Version of the Bible) (a version Joseph Smith supported in the early 1800s). Contrary to popular belief, and that stated at the front of the book, the KJV isn't the original 1600's version, but an update done in the 1770's. And our Book of Mormon English has remained as first published. It seems that the attitude has gone to the idea that we have learnt this language, so everyone can. Yet a few flaws exist in this philosophy.
Firstly a Russian Book of Mormon isn't written in old Russian. And a Romanian Book of Mormon isn't written in old Romanian. So it seems that speaking English is a disadvantage if you have difficulty learning an old version of your language.
Secondly, having worked with adults who have difficulty reading, it is straight out proposterous getting them to read a Book of Mormon. I ended up translating part of 1st Nephi, into English that they could read Click here to read it. It still has some very difficult words, as I didn't want to take risks of wrong translation. But at least it is understandable.
Thirdly, I quote things from the KJV when I really don't know the meaning of some words in them. I have always just made an assumption. "I trow not" (Luke 1:9). What average person would know what "trow" means? We just assume from the flow of converstation. Then there is the word "let", which to us means to allow. But then it meant to stop, or not allow.
Also a philosophy exists that by learning old English we can pray in a special language. That is true. But I would question how Nephi got past not praying in some ancient Hebrew dialect? And how does everyone who isn't speaking English get by? Were Jesus' prayers in ancient Hebrew?
I like being able to impress people outside the church by my ability to rattle off old English, too (not that I do that often, but it happens). But in the interest of spreading the gospel, and delivering it to all mankind equally, I think it time we started making a transition to understandable English.