They definitely like interest, so a LOI can only help. I never sent a LOI, but I reach out to their office after interviewing to learn more about one of their student groups. I think they just like when people show genuine interest and excitement in the school. I ended up getting accepted in December and got called with a full tuition scholarship yesterday. If you want to get connected to a student with a specific interest or identity, you can also request that they put you in touch. I'm pretty sure they encouraged that on my interview day.