How important is it for the marketing professional to be researcher by default?

I already love you for asking :) 

Personally, I think it is absolutely crucial. All normal marketing practices must be client oriented. One of definitions of marketing (which I prefer) is a field of knowledge on how to reach mutual satisfaction between seller and buyer. You need to study your clients (!!!!!!) all the time. You need to know what challenges they face, what are the expectations they have from the product, what kind of problems they expect you to solve for them. And this is a thin materia. Common nigligence of research techniques leads to creation of "perceived value", not actual. That what we think customers want without bothering to ask them. 

You can buy a market report made by professionals, but nobody except you (assuming you are a marketing manager) will study your clients. And unfortunately it is typical in dubai to see marketing managers who faint when hear words like dispersion, correlation or median.

Marketing includes promotion, advertising and management, but it is indeed based on research, statistics and intelligence management.