There is no way I would eat dinner in the buffet unless for a very good reason - scenic cruising for example. I want to have a leisurely meal served to me, while chatting to other passengers. I also struggle to walk unaided now, and since buffets are almost always on the highest decks, that makes it an even worse option if the seas are bumpy. I would rather pay more upfront and know that I can go to the MDR and be seated immediately.