The first few years that I kept house, I thought that shelf liner was too ’50s housewife’ for me! I didn’t see the need for it, thought that it was just being persnickity. Boy, was I wrong. Most cupboard shelves are made from MDF or pressboard and need to be protected from damp dishes and everything else. Your cupboard shelves just get destroyed without it. And it makes them far easier to clean (when you finally break down and do it).
You can use anything you want for the job, as long as it has a relatively waterproof surface. Mactac is often used but kind of hard to apply neatly and the low tad shelf liners are really easy to use but pretty uninspired – but functional. Vinyl wallpaper works well. Oil cloth, cut to fit and laid in place can be a funky and colourful alternative. although it has no adhesive, it is heavy and stays put well. Even way paper is fine. That lumpy, non-skid stuff that you buy in rolls, works well, but you can’t slide things in and out very well. In other words, anything that is slightly moisture proof, easy to cut and lay and also removable, is fine. (It is far nicer to wipe or replace than scrubbing out marked and bubbled shelves.
So the answer is that it doesn’t really matter if it is dowdy or cool, it is just plain necessary, so have some fun with it!