Absolutely right, But, Actually that is very difficult to do many entrepreneurs and on average they like to speculate, initially come with a good concept, pure and very maintain performance. slowly they themselves change the menu to be ordinary.
Actually the more products there are, the more choices there will be for users to choose which one is worth buying because the basic principle is liking and being interested in the products offered.
When you are just starting you will want to reduce a a lot of things because what of you spend money on things that are not important and you need to draft out a plan so that you don't make decisions out of a tin air you have everything planned out and you will know what to do at a particular time. What matters the most is when you have a good plan ahead on your establishment because a lot of people complain about how they have gotten half way and the plan starts failing.
And you need to strength how you manage your products and marketing will be one of the tools that will help you with demand since supply will be taking Care of and you don't have to worry, just make demand your priority and everything will go smoothly. And true marketing you will be able to make them decide exactly the product you are going to sell for them, how you convince this people should be another priority so you focus on when you are doing business.