Agreed that it comes across as rude in English when used on another person in a demanding manner. I can say it as a statement of fact without it being rude, I feel. Also, the point is to learn the Russian language, not idiomatically correct English translations for the Russian language. :)
In addition to what Theron126 has already said, rice is not a traditional Russian food, so we definitely don't have any special plates designated for that purpose.
On the other hand, in Russian we make a distinction between "мелкие/плоские тарелки"="shallow/flat plates" (i.e., just "plates" in English) and "глубокие тарелки"="deep plates" (i.e., "bowls" in English). In the case of rice, I would typically be asking for the second kind, hence I would translate this sentence to English as "I would like a bowl of rice".
EDIT: Incorrect, made a mistake. Keeping for posterity.
basing off the questions that say I want a bowl of soup, wouldn't it also be a plate of rice meaning:
[I want a plate] Accusative (which it is) [of rice] genitive (which it isn't, it's in nominative)
риси - Genitive rice риса - Nominative rice
what's going on?
(Continuing on, and seeing similar sentence structures and only seeing genitive and not nominative, I think this is a mistake)