I can’t imagine lack of food will ever be a real problem (similarly as it is in Pillars of Eternity2). Food in EA was plentiful, and I imagine it will be on sale as well.

Perhaps, it could encourage players to optimise (use max spells before long rest, not spam long rest if unnecessary). There are scenarios where it could go wrong (food too hard to get, too fiddly to manage, too much food required on higher levels) but I wouldn’t be worried about that stuff. If anything it sounds more like “fluff” mechanic, that hard limitation - it should help in encouraging fun gameplay habits though.