Your perspective is wrong. MSC is not a low-cost line, that maybe is your US centric view, because some US lines like Disney are ridiculous expensive. MSC is Italian, even some guys at MSC USA seem to dilute the experience because they think this is needed to conquer the market. I guess many people cannot manage a holiday in Italy, so they also have problem with a MSC cruise. That is where the *sorry* dumb reviews with the "inedible food and rude crew" come from.
MSC is the untouched number one on the European market, everywhere, even the markets in Italy, Germany or UK are so different. That is because they provide a quality experience. Certainly not matching the lines with double prices.