This option is a necessity during COD checkout to provide the upper limit (of order amount) for COD orders.
In the present shipping policies, there is no option to set the maximum amount of order which can be served under COD checkout option.
It is not always possible to provide COD to the large orders specially orders with amount more than Rs. 15,000 or so.
Thank you for your valuable feedback.This Feature Request has already been planned but has been deferred and should be implemented in the updates to come in a couple of months.