That simply doesn't make any sense. I would submit that if you can tell the difference between singular and plural in spoken language, you can tell the difference when you are reading. I will defer to others as to the validity of your points regarding translation, but the continued defense of KJV pronouns in light of today's usage of pronouns seems a bit like stubborness.
So why did all the modern translations have to make adjustments for the 'you', to ensure the reader understood that the statement was made for all men and not just Nicodomus.
The South correctly have the expression 'You'll'(not sure of the spelling of it), which gives the plural, but if you just leave 'you' you do not know if it is singluar and plural.
Now, context may help, but you cannot always count on it being clear.