As all programmers do in programming, they think of logic to solve problems, the shortest code to implement, the most efficient code to use, and the most less-memory burden code to apply. Then we all go around the clock programming it and debugging errors. More professional programmers they go further by looking at variables like how it is use, why it is use, and how these variable can be utilize so it is smaller and not a burden to the system. Yes, variables also play an important part in a system. Here, it is not only referring to ABAP but to other major programming languages from a first level programming language to a very high level programming language.
Try to think VARIABLE as the life source of system like blood in our human system.The logic as the system's backbone and brain. The function and modules that make up components of the system. The interface as the eyes, ears, mouth and hands and legs.
VARIABLE in essence is the vital source to run the code. However, infactual, you may argue DATA is the most important thing in the SDLC, but if you think again, without VARIABLE... what will be use to hold these data. VARIABLE can be consider as the CARRIER. Just like a parasite. They find a host, inject the content then let the content to pass on. VARIABLE is the same, they are used to carry something.That something can be of anything like a data that could affect how the system runs. If the content is bad then the VARIABLE passing inthe system will produce bad result. Similarly, if our blood carries a virus then our human body reacts to it. VARIABLE is the most important TRANSPORTER between modules. Without VARIABLES, there will be no communication between modules. LIke humans, we have mouths, we use it to communicate. Therefore, VARIABLES plays an important role in all programming language.
In Matrix's last installment, do you all remember the words or slogan beneath the title, it goes like "Every ending has Starting and every middle has a starting... also ending!". VARIABLEs work in that way.
"There is no lost but just... tracing".
the sky is not the limit...