As long as you get the amount of product that is advertised on the container I don't see anything wrong with it. Not to mention that with instant noodles you need a certain water:noodle ratio, so how would they do it? If they added more noodles, they'd also need more water which would mean more volume in the cup.
/e
Not saying companies aren't playing dirty tricks with container size, content, and such. Putting less stuff into the same sized containers while keeping the price the same is common practice, sadly.