It is not that I am incapable to understand old English, it is that 1600 is dramatically closer to modern than 1400 one; I think someone from 1600 would be able to converse at 2026 UK farmers market with little problems too; someone from 1400 would be far more challenged.
I have read many printed books from the range 1450 to 1900, in several European languages. In all of them the languages are much easier to understand than those of the earlier manuscripts.