To be an inker is to not practice a dying job. It is in the contrary one of the best of the two world of drawing: the digital and the classic one. What is great within these two worlds is that you can not say, when it is well done, what part is digital (except the greytones - of course!!) to what is classical.
And the most important part to this job is to do bring or better, to put life into a drawing. There a lot of excellent drawing artists, but some lack one of a base of an excellent drawing: the force lines. The drawing is very good but it lack from something that says "this is not an excellent drawing". The inker can then, correct and add these force lines and then, the drawing is really alive.
No one is perfect in this time of poorly paid overproduction of mainstream comic books. Time, pressures, censors, editors and publishers put the drawer under a so stressful environment that he lacks always something. The inker and the colourist are their to give these lacking touches in a drawing.
To apprentice artist, the inking process is a wonderful tool to help to improve his/her drawing skills. He/she learns to draw less lines to only keep the best and the most powerful ones. So, for the next drawing, the artist will use more usable and powerful lines in his/her drawing.