I agree that voting should be limited to people in the jam, it makes it fell more like a community effort. I've seen a lot about the ratings causing people with low amounts of ratings to do well while those with higher ratings do worse. While I can see this been a bad thing, I wouldn't try to remove it entirely as otherwise it just falls to who has the most attractive looking game with the best art that has gotten the most attention because of it. While having nice art is always a plus, this jam inparticular as focused on design and at the end of the day. So realistically its just tweaking the formula to work better. I'd also add maybe community engagement (on itch.io) should go into account. maybe number of comments over 100 words. over have a category for best sport based on that factor, just encorages people to review and rate games.
That's my 2 cents on the matter as of writing...