It is the theme author’s responsibility to give an admin interface that will allow the client to create the content in the form he wants. Layout related options and shortcodes are just a way for the author to justify doing a poor job in understanding the client’s needs and helping the client to easily manage his site. (there is some difference between a themes for sale and a theme for specific client but IMO most themes today are bloated and include a lot of functionality which is better deployed as plugin for whoever needs it)
The reason is that if your client would have known HTML/CSS/PHP he would have written his pages by himself and would not have needed you, but your client don’t understand HTML, don’t understand what is responsiveness and don’t have a clue about how to do graphic design, therefor giving the tools for the client to do anything he wants is just helping him to shot himself.
Granted, some clients don’t understand that and think that they actually can design a passable web page by themselves, but if this kind of requirement comes up early in the process of developing a site it means that the client didn’t fully define their requirements.