The whole point of this jam is to be a laid-back thing, where people are free to make what they want using whatever portion of the allotted time they like. Would it be nice if every game submitted was of excellent quality and clearly took a lot of time and effort? Sure, but that's not really realistic or in-theme with the jam.
People only have so much vacation time to spend, and oftentimes plenty of other ways they could spend it, so for a 0-stakes non-competitive jam I wouldn't be too concerned by people making simplistic games. Plus, because this is designed as a very approachable jam, it may very well get submissions by people who are inexperienced with making games. Creating *something* playable is still a significant achievement for many people, no matter how small or unpolished.