This type of instant ramen is the example that economics professors use of an inferior good.

inferior goods are those goods the demand for which falls with increase in income of the consumer

At least, that was the example that my professor used when I went to college. I suspect that a lot of cheap instant ramen is eaten on college campuses even to this day.

So, the point is that you're stating what I think is the right way of looking at this. A big part of the reason people buy this is that they aren't making much money, so naturally, they'd want to buy the cheaper one, as well.