I did not know that Boeing had put a restriction on it's use below 3000'. Could it be a company imposed restriction?(for what ever inane reason they may have come up with)If not could you provide us with the reference?
The B737 EFIS aircraft is designed to fly most efficiently in VNav. Assuming you have input what YOU want the a/c to do.
Experience has proven to me that most people who do not use this function, do not understand this fact and spend most of their time blaming the system rather than learning how to use it.
People could make life easy for themselves by learning the sytems of their a/c thoroughly
b4 flying the damn things.