Psychological effect. Players limit their Long Rest because they realise that food, and thus Long Rest, is a potentially-limited resource, and they fear they might run short at some point.
This only works for so long. A couple of hours in, players realise that they are sitting on mountains of food. Unlike gold, which we will almost inevitably end up impossibly-rich with because I don't think I've seen a video game where the "gold curve" remains credible past the early game, and which we will surely hoard because that's what gold is for, I guess, and, who knows, maybe in this game the best gear will be bought instead of looted, so ... unlike gold, food can't be used for purchasing anything else than Long Rests. That means that once we've figured out how frequently we long rest and how abundant food is, there is no more reason to save food just-in-case. We can spend it fairly carelessly.
Yeah well, you're generalizing a bit too much perhaps. Not my proudest moments but I am one of those people who finishes the OG BG games with insane number of consumable items in their inventory because 'better to hoard, you never know if you might need it later on'. Although a minority, I know there's more of us, OCD inventory hoarders than you might think. (off topic, that's actually a piece of data analysis I would like Larian to present to us near release, like average consumable consumption and looting behavior of players and stuff).
