[Nyororin]

Just last year I helped my friend take her rice to the "senzai"

I think you mean "senmai"
We have a little single serving size machine in our kitchen. The rice tastes better and stays fresher longer if you store it in the brown state and then only polish it before cooking. Also - different meals do better with different levels of polishing, so it`s nice to be able to adjust that on the fly for every meal.

The "best answer" is an interesting look at this. The reason given is 『お金がない人の食事』. In other words, it's considered a "poor man's food".

I think something that you need to keep in mind is that the answers given are of the same level of quality as you might find on Yahoo! Answers. Just because it is the "best" answer doesn`t make it a correct answer. It`s just the one that the asker liked the best. Factuality has little to do with it.

Something can "feel" like a poor person`s food, but not actually have ever been a poor person`s food. I`d say it would fall into the same category as canned tuna on rice - another "poor" food... That has NEVER been cheap (still isn`t), but just has that "feeling". Rice was not cheap in the past - it has only gotten cheaper. But because of the simplicity of the ingredients, and loneliness of the thought of just rice and soy sauce - it feels like something someone with no money might eat.

I`ve tried to come up with something comparable from the US, but can`t as there isn`t really any main diet staple that used to be a sort of gourmet food like rice.
Maybe an easy way to think of it would be, say, making cereal with tap water instead of milk. It seems so... poor. But the cereal (let us assume it`s the brand name, too much for what it is type) itself is NOT cheap, so if you really think about it, it`s just something that feels poor. A real poor person wouldn`t have the money to buy the cereal - just as a poor person in the past in Japan wouldn`t have been able to buy the rice. They`d be eating something else.