This would assume that most readers actually read footnotes. I doubt this is the case.
What makes you think it has a 10th grade reading level? What is this based on?
This is false. The only thing it demonstrates is that the English language is different 400 years later. This is no different than the reality that the English Language of the KJV was different than it was 400 years prior to that. This is a non-starter argument and it is not reality.
No, English has not gone downhill. It's become more-practical, with spelling simplified more. And it takes its users' intelligence into account. For instance, most people know whether a particular use of "you" is singular or plural. And it's eliminated the unnecessary "eths, ests", etc. It's an IMPROVED English that expresses something more-quickly.
I'm saying that sentence structure, punctuation, and word meanings are all different than they are now. Does this mean you can't read and understand the KJV? Not necessarily. But nobody today reads and understands the KJV without extra dictionaries (and these must be specific dictionaries, simple Webster will not help you) and understanding the language of the 17th century vs the 21st century.
In short, no, nobody today reads the KJV just as it is without any helps and can understand the English plainly. If you say that you can you are either ignorant or lying to yourself.