Right now I'm in my Junior year of undergrad, and I haven't really made any mods of any game so far, though I did tinker around with the Quake 2 gameplay code for a bit, which was quite fun. I also liked the Wolf3D mod scene, and played around with the level editors when I was a kid
So, currently I'm learning graphics programming, and already at the level where I could get a basic 3D scene up and running with lighting and textures. But your insight has raised a question in my head - should I continue learning graphics programming? Or should I just work on game/gameplay programming instead for my portfolio, then learn graphics/engine programming while working as a game programmer?
All these options sound really exciting, that's why it's difficult for me to make a decision.It's hard to give advice because we're not in your situation, and our situations won't necessarily apply to yours
My general advice is that by the time you graduate, you should have at least a small standalone-game or a total-conversion-mod, or a collection of small mods, or a research project demonstrating a new innovation. Generally I would say that you should have made this in your own time (not schoolwork) however there's always exceptions, e.g. many "game schools" allow you to do a large group project during final year, which often results in quite an impressive/large game... or if you're doing a thesis you might have some great innovation/research to show off.
In your case, if you're interested in graphics, then making a small game (even an 80's arcade game remake) would be great if you can say that it's running on your own graphics framework instead of an existing engine. In an interview, you can then have deep conversations about how this framework works.
It's usually short-sighted (and frankly a bit sociopathic) to base decisions just on the state of the market, but at the moment, there is huge market demand for graphics programmers. e.g. I have companies in the USA offering to double my salary if I wanted to move to that country and do senior graphics programming work. So assuming that this demand sticks around, that's a good incentive to follow your interest and keep learning in this area.
It's hard to get into a graphics job as a junior/graduate, but you might get lucky if you're in the right place and the right time. Otherwise, it's always a plus to have on your resume if you're trying to get a junior/graduate gameplay programming job - it might make you stand out more against other candidates if you can write gameplay code but also have demonstrable knowledge of graphics stuff. It means if they invest the time in taking you on, then they'll have the option of moving you into the engine team later. It's nice if in an interview you can express an interest and show a bit of knowledge in engine/tools/tech-art areas as well, to show your value as a generalist and a strong self-learner.
So basically, try to learn gameplay and graphics if you're interested in both
All right then, I've decided to continue with learning graphics programming, making my own graphics framework in the process, and create a working demo game using that engine/framework before I graduate.
Thanks a lot for the advice! I will always keep it in mind to motivate myself 
