Dear thuygtn,
The problem in not creating a gallery, the problem is editing it. For us web developers we can work with it, for the client/end user who has no coding knowledge and frankly now our days, they don't have to, it is difficult for them to edit. One of the point of using Joomla or any other CMS is for client to be able to edit the content easily.
And it is not only gallery but shorcode in general. How an end user edit an already inserted shortcode in the article? They have to go throught the code and edit manually.
My wish is to have an easier way to edit. It is very easy to insert a shortcode, it should be easy also to edit one.